Vascular, adipose tissue, and/or calyceal invasion in clear cell tubulopapillary renal cell tumour: potentially problematic diagnostic scenarios

AIMS

The 2022 WHO classification for kidney tumours recently downgraded clear cell tubulopapillary (also known as clear cell papillary) renal cell carcinoma (RCC) to a benign neoplasm (i.e. clear cell tubulopapillary renal cell tumour) based on the overwhelmingly banal nature of this neoplasm. However, it has been recognized that some clear cell tubulopapillary renal cell tumours demonstrate vascular, adipose or pelvicalyceal invasion, raising the possibility of more aggressive behaviour. The goal of this study was to determine if these 'high stage' features have an effect on tumour prognosis, warranting a carcinoma designation.

METHODS AND RESULTS

After excluding cases with tissue artefact (i.e. prior core biopsy track changes) and other RCC subtypes with next-generation sequencing, nine clear cell tubulopapillary renal cell tumours with these so-called 'high stage' features, and otherwise classic morphologic and immunophenotypic findings, including low-grade cytology and 'cup-like' CA9 expression, were evaluated. Median tumour size was 2.2 cm with a range of 0.8 to 6.7 cm. Eight cases (89%) demonstrated perinephric or hilar adipose tissue invasion, although most of these cases showed a bulging (in contrast to an infiltrative) growth pattern. One case demonstrated renal vascular invasion in addition to hilar adipose tissue invasion, and one case demonstrated extension into the pelvicalyceal system. There were no recurrences or evidence of metastatic disease.

CONCLUSION

These overall findings continue to support the benign designation for clear cell tubulopapillary renal cell tumours, despite morphologic features that might raise the possibility of a 'higher stage' neoplasm.

Current gross examination and reporting patterns of post-neoadjuvant chemotherapy cystectomy specimens: Is it time for a standardized approach?

OBJECTIVES

Neoadjuvant chemotherapy (NACT) is recommended for muscle-invasive bladder cancer, and robust treatment response may result in lack of grossly identifiable tumor in the cystectomy specimen. Current gross examination and reporting protocols, however, do not include specific guidance on the approach to these specimens.

METHODS

A Qualtrics survey was disseminated by email and X (formerly Twitter). Responses from pathologists and pathologists' assistants (PAs) were included. The survey interrogated demographics, practice settings, prevalence of NACT use, approach to gross examination, and reporting practices in the setting of both grossly visible tumor or ulcer bed and the complete absence of a gross lesion.

RESULTS

Based on 55 respondents' experience, identifying gross tumor occurred less frequently than tumor or ulcer bed (40% vs 71%). Lack of identification of any gross lesions was estimated to occur in 29% of cases. Gross examination practices were relatively consistent in cases with residual gross tumor or gross tumor bed, with agreement that gross tumor should be submitted as 1 block per centimeter (66%), and tumor or ulcer bed should be submitted in its entirety (97%). Gross examination practices appeared more varied when no gross lesions were identified. Overall, most responders stated they "definitely" or "maybe" support a standardized gross examination (89%) and reporting (96%) protocol.

CONCLUSIONS

With the increased use of NACT, lack of any gross lesion leads to inconsistent gross examination techniques. This study provides insight into the current approach to examination of post-NACT cystectomies and suggests that a desire exists among pathologists and pathologists' assistants for more standardized practice.

Molecular Characterization of Juxtaglomerular Cell Tumors: Evidence of Alterations in MAPK-RAS Pathway

Juxtaglomerular cell tumor (JGCT) is a rare neoplasm, part of the family of mesenchymal tumors of the kidney. Although the pathophysiological and clinical correlates of JGCT are well known, as these tumors are an important cause of early-onset arterial hypertension refractory to medical treatment, their molecular background is unknown, with only few small studies investigating their karyotype. Herein we describe a multi-institutional cohort of JGCTs diagnosed by experienced genitourinary pathologists, evaluating clinical presentation and outcome, morphologic diversity, and, importantly, the molecular features. Ten JGCTs were collected from 9 institutions, studied by immunohistochemistry, and submitted to whole exome sequencing. Our findings highlight the morphologic heterogeneity of JGCT, which can mimic several kidney tumor entities. Three cases showed concerning histologic features, but the patient course was unremarkable, which suggests that morphologic evaluation alone cannot reliably predict the clinical behavior. Gain-of-function variants in RAS GTPases were detected in JGCTs, with no evidence of additional recurrent genomic alterations. In conclusion, we present the largest series of JGCT characterized by whole exome sequencing, highlighting the putative role of the MAPK-RAS pathway.

Chromophobe Renal Cell Carcinoma With Extensive Retraction Artifact: A Potential Diagnostic Pitfall From Micropapillary Urothelial Carcinoma

In addition to "classic" and eosinophilic subtype, chromophobe renal cell carcinoma (RCC) is well-known to demonstrate various morphological patterns including adenomatoid, microcystic, pigmented, multicystic, papillary, neuroendocrine-like, and small cell-like, all of which are important to appreciate for accurate diagnosis. Herein, we expand on a unique chromophobe RCC morphology not previously described consisting of tumor cells with extensive stromal retraction, mimicking upper urothelial tract micropapillary carcinoma (MPC). Twelve MPC-like chromophobe RCC nephrectomies were reviewed with clinicopathological features recorded; molecular testing was performed on 7 of 12 tumors. Patients were mostly men (n=10) with a mean age of 65 years. Mean tumor size was 6.4 cm with pathological stage distribution as follows: 4 (33%) T1a, 2 (17%) T1b, 1 (8%) T2b, and 3 (25%) T3a. The extent of MPC-like chromophobe RCC foci ranged from 10% to 40% (mean=26%; there was no correlation between the extent of MPC-like chromophobe RCC foci and tumor stage). Other chromophobe RCC morphological patterns were not identified. When performed, all (100%) tumors depicted prototypic chromophobe RCC staining pattern of KIT positivity/KRT7 positivity. Molecular showed 6 of 7 (86%) with multiple chromosomal losses. Clinically significant mutations were identified in NF1, TP53, FLCN (likely somatic), CHEK2, and ZFHX3 genes. Follow up available in 9 patients showed no evidence of disease (mean=23 months). Although the etiology behind the extensive stromal retraction in our tumors is unknown, this may likely be artifactual in nature. Nonetheless, it is important to include MPC-like chromophobe RCC in the spectrum of "variant" morphologies to avoid diagnostic pitfalls from micropapillary carcinoma.

GATA3 Expression in Prostatic Adenosquamous Carcinoma: A Potential Diagnostic Pitfall

Urothelial carcinoma and prostatic adenocarcinoma can have overlapping histologic features and in some instances pose challenges to pathologists. GATA binding protein 3 (GATA3) immunohistochemistry (IHC) is a well-established tool to aid in this specific diagnostic dilemma as it has been shown to be a sensitive marker for urothelial carcinoma and a putatively specific marker in excluding prostatic adenocarcinoma. However, in encountering an index tumor of prostatic adenosquamous carcinoma positive for GATA3, herein we sought to investigate this potential diagnostic pitfall in a larger series of tumors. In this study, we retrospectively reviewed prostatic adenosquamous carcinomas diagnosed in 17 patients across the authors' institutions and personal consult collections in the past 10 years. GATA3 IHC was either reviewed or performed on tumors not previously tested. We also recorded other immunostains that were performed at initial diagnosis. Positivity for GATA3 was found in 9 of 17 (53%) tumors, all within squamous regions (2 tumors also showed concomitant moderate GATA3 positivity within glandular elements). The GATA3 positive tumors were all positive for p63 in the 7 tumors where p63 was also performed. Of all tumors tested, NKX3.1 was positive in 100% (13/13) of the glandular elements (3 tumors also showed NKX3.1 concomitant positivity within squamous regions). In summary, when encountering a carcinoma with mixed glandular/squamous features in which prostatic origin is being considered, awareness of GATA3 immunoreactivity in a subset of prostatic adenosquamous carcinoma is critical to avoid diagnostic pitfalls.

Topline/Final Diagnostic Inclusion of Relevant Histologic Findings in Surgical Pathology Reporting of Carcinoma in Prostate Biopsies

INTRODUCTION

As the list of histologic parameters to include in surgical pathology reports of prostate cancer biopsies grows, some pathologists include this information in the microscopic description or summary sections of the report, whereas others include it in the "topline" or final diagnosis section. This prompted us to develop a multi-institutional survey to assess reporting trends among genitourinary (GU) pathologists.

METHODS

A survey instrument was shared among 110 GU pathologists via surveymonkey.com. Anonymized respondent data was analyzed.

RESULTS

Eighty-four (76%) participants completed the survey across four continents. Most participants report tumor volume quantitation (88%), number of cores involved (89%), and both Gleason grade and Grade group (93%) in their topline; 71% include percent of pattern 4, with another 16% including it depending on cancer grade; 58% include the presence of cribriform growth pattern 4, with another 11% including it depending on cancer grade. When present, most include extraprostatic extension (90%), prostatic intraductal carcinoma (77%), and perineural invasion (77%). Inclusion of atypical intraductal proliferation (AIP) in the topline diagnosis was cancer grade-dependent, with 74% including AIP in Grade group 1, 61% in Grade group 2, 45% in Grade group 3, 30% in Grade group 4, and 26% in Grade group 5 cancers.

CONCLUSION

Certain histologic features such as Gleason grade and tumor volume/cores involved are frequently included in the topline diagnosis, whereas the incorporation of other findings are more variably included. Prostate biopsy reporting remains a dynamic process with stylistic similarities and differences existing among GU pathologists.

Patterns of B-cell lymphocyte expression changes in pre- and post-malignant prostate tissue are associated with prostate cancer progression

BACKROUND

Inflammation characterized by the presence of T and B cells is often observed in prostate cancer, but it is unclear how T- and B-cell levels change during carcinogenesis and whether such changes influence disease progression.

METHODS

The study used a retrospective sample of 73 prostate cancer cases (45 whites and 28 African Americans) that underwent surgery as their primary treatment and had a benign prostate biopsy at least 1 year before diagnosis. CD3+, CD4+, and CD20+ lymphocytes were quantified by immunohistochemistry in paired pre- and post-diagnostic benign prostate biopsy and tumor surgical specimens, respectively. Clusters of similar trends of expression across two different timepoints and three distinct prostate regions-benign biopsy glands (BBG), tumor-adjacent benign glands (TAG), and malignant tumor glandular (MTG) regions-were identified using Time-series Anytime Density Peaks Clustering (TADPole). A Cox proportional hazards model was used to estimate the hazard ratio (HR) of time to biochemical recurrence associated with region-specific lymphocyte counts and regional trends.

RESULTS

The risk of biochemical recurrence was significantly reduced in men with an elevated CD20+ count in TAG (HR = 0.81, p = 0.01) after adjusting for covariates. Four distinct patterns of expression change across the BBG-TAG-MTG regions were identified for each marker. For CD20+, men with low expression in BBG and higher expression in TAG compared to MTG had an adjusted HR of 3.06 (p = 0.03) compared to the reference group that had nominal differences in CD20+ expression across all three regions. The two CD3+ expression patterns that featured lower CD3+ expression in the BBG compared to the TAG and MTG regions had elevated HRs ranging from 3.03 to 4.82 but did not reach statistical significance.

CONCLUSIONS

Longitudinal and spatial expression patterns of both CD3+ and CD20+ suggest that increased expression in benign glands during prostate carcinogenesis is associated with an aggressive disease course.

Are Renal Tumor Diagnostics Becoming Too Advanced for Many Pathology Laboratories?

The recent influx of novel renal neoplasms, particularly molecularly-defined renal carcinomas, has introduced new challenges in the daily practice of most pathology laboratories. These tumors are uncommon, they do not always have well-established morphologic features, and the expression profile of most common biomarkers is not well understood. Moreover, the diagnosis of molecularly-defined renal carcinomas requires the documentation of the disease-defining molecular alteration, with molecular studies or surrogate immunohistochemical markers. Unfortunately, most pathology laboratories lack molecular laboratories, or it is not cost-effective to maintain assays of the specific biomarkers in these unusual tumors. Pathologists should have updated knowledge about the recent changes in renal neoplasms and be aware of these limitations.

Mechanistic Target of Rapamycin Kinase is a Common Convergent Pathway to Renal Neoplasia: A Contemporary Review

Mechanistic target of rapamycin kinase (mTOR) is a member of the phosphatidylinositol-3-hydroxide kinase (PI3 K)-related protein kinase family that functions as a central regulator of cell growth, metabolism, proliferation, and survival. The role of the TSC-mTOR signaling pathway in kidney tumors has been implicated in some hamartoma syndromes; however, with the advent and wide utilization of molecular studies, a growing number of kidney tumors have been linked to somatic or germline mutations involving genes that encode for this pathway, including eosinophilic solid and cystic renal cell carcinoma, low-grade oncocytic tumor, eosinophilic vacuolated tumor, renal cell carcinoma with fibromyomatous stroma and angiomyolipoma, among others. Herein, we review the contemporary developments of mTOR pathway-related renal neoplasia, focusing on the clinicopathologic features of the tumor entities.

Adenoid cystic carcinoma metastatic to the kidney: a series of 10 patients emphasizing unilateral presentation and long time interval from primary diagnosis

Adenoid cystic carcinoma (AdCC) metastasis to kidney is rare. We identified 10 patients with metastatic AdCC in multi-institutional collaboration. Core needle biopsy was the most common specimen (n = 6). Patients were predominately female (n = 7) with a median age of 48 years (35-62 years). The most common primary location of the AdCC was head and neck (n = 6, among them parotid gland = 4), followed by lung (n = 2), breast (n = 1), and vulva (n = 1). Median lapse between primary AdCC and renal metastasis was almost 13 years (154 months, range 1-336 months). Moreover, all but one patient had unilateral kidney metastasis. The majority of metastatic AdCC within the kidney demonstrated mixed growth patterns, frequently cribriform, and tubular morphology. Follow-up available for 8 patients showed 6 alive with disease and 2 died of disease (the longest survival was 4 years past the diagnosis of renal metastasis). A systematic literature review including 29 patients revealed that kidney metastasis by AdCC is usually a late event, is typically unilateral, and is usually composed of one to three foci, and thus has clinical features which mimic a primary renal tumor.

International Society of Urological Pathology (ISUP) Consensus Conference on Current Issues in Bladder Cancer: Working Group 3: Subcategorization of T1 Bladder Cancer

Emerging data on T1 bladder cancer subcategorization (aka substaging) suggests a correlation with oncological outcomes. The International Society of Urological Pathology (ISUP) organized the 2022 consensus conference in Basel, Switzerland to focus on current issues in bladder cancer and tasked working group 3 to make recommendations for T1 subcategorization in transurethral bladder resections. For this purpose, the ISUP developed and circulated a survey to their membership querying approaches to T1 bladder cancer subcategorization. In particular, clinical relevance, pathological reporting, and endorsement of T1 subcategorization in the daily practice of pathology were surveyed. Of the respondents of the premeeting survey, about 40% do not routinely report T1 subcategory. We reviewed literature on bladder T1 subcategorization, and screened selected articles for clinical performance and practicality of T1 subcategorization methods. Published literature offered evidence of the clinical rationale for T1 subcategorization and at the conference consensus (83% of conference attendants) was obtained to report routinely T1 subcategorization of transurethral resections. Semiquantitative T1 subcategorization was favored (37%) over histoanatomic methods (4%). This is in line with literature findings on practicality and prognostic impact, that is, a shift of publications from histoanatomic to semiquantitative methods or by reports incorporating both methodologies is apparent over the last decade. However, 59% of participants had no preference for either methodology. They would add a comment in the report briefly stating applied method, interpretation criteria (including cutoff), and potential limitations. When queried on the terminology of T1 subcategorization, 34% and 20% of participants were in favor of T1 (microinvasive) versus T1 (extensive) or T1 (focal) versus T1 (nonfocal), respectively.

Nested and Large Nested Subtypes of Urothelial Carcinoma of the Upper Urinary Tract: A Multi-institutional Study

Nested urothelial carcinoma (NUC) and large nested urothelial carcinoma (LNUC) of the upper urinary tract are exceedingly rare. This has contributed to the paucity of information regarding their clinicopathological and molecular characteristics. To address this knowledge gap, we explored the largest cohort to date of these rare tumors, comprising resection specimens of 10 LNUC and 7 NUC, from 7 participating institutions. Clinicopathological data were retrieved and documented. Whole exome sequencing and RNA sequencing were performed on the Illumina NovaSeq 6000 sequencer. The data generated were analyzed using the genome analysis toolkit pipeline. Somatic mutations were annotated using funcotator tool to identify pathogenic/likely pathogenic variants. Tumor mutational burden was calculated using python-based "pyTMB" tool. Microsatellite instability analysis was done using MSIsensor2 and the Idylla platform. Differential expression analysis of genes in LNUC and NUC along with mRNA expression-based molecular subtyping was performed by analyzing expression pattern of markers used in The Cancer Genome Atlas subclassification of bladder carcinoma. Both tumor types were more common in older males, were unifocal, and occurred more commonly mixed with minor components of predominantly conventional urothelial carcinoma. Overlying low-grade papillary urothelial carcinoma was significantly more common in LNUC (P = .034). On follow-up (LNUC: median, 10 months; range, 3-84 months; NUC: median, 9 months; range, 2-48 months), LNUC had better clinical outcomes (P = .031). Pathogenic mutations in FGFR3 and PIK3CA were significantly more common in LNUC (P = .049 and P = .044, respectively), with the latter present exclusively in LNUC. Seventy-five percent of the cases showed tumor mutational burden of <10, and all cases were microsatellite-stable. FGFR3 mutations were also more common in low-stage tumors. This study expands on the clinicopathological spectrum of NUC and LNUC of the upper urinary tract and is the first to comprehensively analyze the molecular profile of these tumors, highlighting pathogenic genetic alterations of potential therapeutic and prognostic value.

Reporting Trends, Practices, and Resource Utilization in Neuroendocrine Tumors of the Prostate Gland: A Survey among Thirty-Nine Genitourinary Pathologists

Background. Neuroendocrine differentiation in the prostate gland ranges from clinically insignificant neuroendocrine differentiation detected with markers in an otherwise conventional prostatic adenocarcinoma to a lethal high-grade small/large cell neuroendocrine carcinoma. The concept of neuroendocrine differentiation in prostatic adenocarcinoma has gained considerable importance due to its prognostic and therapeutic ramifications and pathologists play a pivotal role in its recognition. However, its awareness, reporting, and resource utilization practice patterns among pathologists are largely unknown. Methods. Representative examples of different spectrums of neuroendocrine differentiation along with a detailed questionnaire were shared among 39 urologic pathologists using the survey monkey software. Participants were specifically questioned about the use and awareness of the 2016 WHO classification of neuroendocrine tumors of the prostate, understanding of the clinical significance of each entity, and use of different immunohistochemical (IHC) markers. De-identified respondent data were analyzed. Results. A vast majority (90%) of the participants utilize IHC markers to confirm the diagnosis of small cell neuroendocrine carcinoma. A majority (87%) of the respondents were in agreement regarding the utilization of type of IHC markers for small cell neuroendocrine carcinoma for which 85% of the pathologists agreed that determination of the site of origin of a high-grade neuroendocrine carcinoma is not critical, as these are treated similarly. In the setting of mixed carcinomas, 62% of respondents indicated that they provide quantification and grading of the acinar component. There were varied responses regarding the prognostic implication of focal neuroendocrine cells in an otherwise conventional acinar adenocarcinoma and for Paneth cell-like differentiation. The classification of large cell neuroendocrine carcinoma was highly varied, with only 38% agreement in the illustrated case. Finally, despite the recommendation not to perform neuroendocrine markers in the absence of morphologic evidence of neuroendocrine differentiation, 62% would routinely utilize IHC in the work-up of a Gleason score 5 + 5 = 10 acinar adenocarcinoma and its differentiation from high-grade neuroendocrine carcinoma. Conclusion. There is a disparity in the practice utilization patterns among the urologic pathologists with regard to diagnosing high-grade neuroendocrine carcinoma and in understanding the clinical significance of focal neuroendocrine cells in an otherwise conventional acinar adenocarcinoma and Paneth cell-like neuroendocrine differentiation. There seems to have a trend towards overutilization of IHC to determine neuroendocrine differentiation in the absence of neuroendocrine features on morphology. The survey results suggest a need for further refinement and development of standardized guidelines for the classification and reporting of neuroendocrine differentiation in the prostate gland.

Metastatic solid tumors to the testis: a clinicopathologic evaluation of 157 cases from an international collaboration

To elucidate the spectrum of metastatic solid tumors to the testis and their clinicopathologic features. The databases and files of 26 pathology departments from 9 countries on 3 continents were surveyed to identify metastatic solid tumors to the testis and to characterize their clinicopathologic features in detail. We compiled a series of 157 cases of metastatic solid tumors that secondarily involved the testis. The mean patient age at diagnosis was 64 years (range, 12-93 years). Most patients (127/144; 88%) had clinical manifestation of the disease, with testicular mass/nodule (89/127; 70%) being the most common finding. The main mechanism of testicular involvement was metastasis in 154/157 (98%) cases. Bilateral testicular involvement was present in 12/157 (8%) patients. Concurrent or prior extratesticular metastases were present in 78/101 (77%) patients. The diagnosis was made mainly in orchiectomy specimens (150/157; 95%). Different types of carcinomas (138/157; 87%), most commonly adenocarcinoma (72/157; 46%), were the most common malignancies. The most common primary carcinomas included prostatic (51/149; 34%), renal (29/149; 20%), and colorectal (13/149; 9%). Intratubular growth was identified in 13/124 (11%) cases and paratesticular involvement was found in 73/152 (48%) cases. In patients with available follow-up (110/157; 70%), more than half (58/110; 53%) died of disease. In this largest series compiled to date, we found that most secondary tumors of the testis represent metastases from the genitourinary and gastrointestinal tract carcinomas and typically occur in the setting of disseminated disease.

Artifactual Cystic Spaces in Prostatic Transurethral Resections and Related Specimens: A Potential Diagnostic Confounder

Aims. Histopathologic benign mimickers of prostate cancer have mostly focused on glandular mimics, with non-glandular mimics mainly limited to inflammatory conditions. While there is a paucity of literature recognizing small cystic (presumably artifactual) spaces in transurethral resection specimens, in some instances they can become florid enough to mimic vascular or epithelial neoplasms. Herein, we detailed histologic, immunophenotypic, and clinicopathologic findings in a large series of specimens showing prominent diagnostically confounding cystic spaces. Methods and Results. Sixty specimens were obtained (50 transurethral resections, 7 aquablations, 3 laser enucleations), from 17 different surgeons. Seven specimens had concurrent genitourinary pathology (4 prostatic adenocarcinoma, 1 solitary fibrous tumor, 1 prostatic atypia, 1 urothelial carcinoma in situ). The extent of cystic change among overall tissue examined ranged from 1 mm-8 mm (mean 3.4 mm), with luminal content of cystic spaces characterized as empty (72%), both empty and fluid-like (17%), and both empty and mucin-like (11%; mucin histochemical stain was negative on all specimens). Notable differences in degree of tissue cautery artifact or inflammation was not found. Immunohistochemistry performed on 30 specimens showed cystic spaces negative for S100, ERG, pankeratin, and CD45. Conclusion. Although artifactual in nature, in some instances small cystic spaces encountered in prostatic transurethral resections and more novel related procedures can become florid enough to warrant recognition as a potential diagnostic confounder of vascular or epithelial neoplasms.

Renal Neoplasia Occurring in Patients With PTEN Hamartoma Tumor Syndrome : Clinicopathologic Study of 12 Renal Cell Carcinomas From 9 Patients and Association With Intrarenal "Lipomas"

The aim of this study was to assess the histopathologic spectrum of renal tumors in patients with PTEN hamartoma tumor syndrome (PHTS), with a specific focus on potential features predictive of the underlying syndrome. A multi-institutional study was conducted to obtain clinical and pathologic data on renal tumors arising in patients with PHTS, either diagnosed by germline mutational analysis or clinical criteria for Cowden syndrome. Histologic sections of the renal tumors were re-reviewed for classification. Twelve renal epithelial tumors from 9 patients were identified (4 males and 5 females, with a mean age of 41.8 y), 7 of whom carried germline PTEN mutations. All 12 renal epithelial tumors were renal cell carcinomas (RCCs): 5 were chromophobe RCCs, 4 papillary RCCs, and 3 RCC not otherwise specified. Pathologic stage distribution was: 7 (59%) pT1a, 2 (17%) pT1b, 1 (8%) pT2a, 1 (8%) pT2b, and 1 (8%) pT3a. World Health Organization/International Society of Urological Pathology (WHO/ISUP) histologic grade was applicable in 7 (54%) nonchromophobe tumors: 4 (57%) G2, 2 (29%) G3, and 1 (14%) G4. An unexpected histologic finding was the presence of 2 patients with incidental microscopic collections of intrarenal adipocytes that had no features of angiomyolipoma (and were negative with 2 sensitive PEComa markers: cathepsin-K and GPNMB); both were classified as lipoma/"lipomatous hamartomas." The average follow-up interval was 67.8 months (13 to 172 mo): 5 patients had no evidence of disease, 2 were lost to follow-up, 1 died of other (non-PHTS) causes (ie, prostate cancer), and 1 was alive with metastatic RCC to the lung (RCC not otherwise specified with rhabdoid differentiation). All tumors showed loss of nuclear PTEN staining by immunohistochemistry. Fumarate hydratase was retained and 2SC was negative in all papillary RCCs. CK7 was moderate-strong/diffuse positive in 4 of 5 chromophobe RCCs and in 3 of 4 papillary RCCs. Renal epithelial tumors associated with PHTS represent a heterogeneous group of RCCs, but classic chromophobe and papillary RCC are most common. The majority have a favorable clinical behavior as would be predicted by subtype. In contrast to other hereditary renal neoplasia syndromes, morphologic features of the RCCs do not allow identification of PHTS-associated neoplasia with any degree of specificity in the absence of clinical setting and/or prior history, but the presence of microscopic "lipomas" within the kidney may provide a clue in rare cases. Therefore, clinical suspicion and genetic counseling with germline testing remain necessary for identifying PHTS-associated RCC.

International Opinions on Grading of Urothelial Carcinoma: A Survey Among European Association of Urology and International Society of Urological Pathology Members

Background

Grade of non-muscle-invasive bladder cancer (NMIBC) is an important prognostic factor for progression. Currently, two World Health Organization (WHO) classification systems (WHO1973, categories: grade 1-3, and WHO2004 categories: papillary urothelial neoplasm of low malignant potential [PUNLMP], low-grade [LG], high-grade [HG] carcinoma) are used.

Objective

To ask the European Association of Urology (EAU) and International Society of Urological Pathology (ISUP) members regarding their current practice and preferences of grading systems.

Design setting and participants

A web-based, anonymous questionnaire with ten questions on grading of NMIBC was created. The members of EAU and ISUP were invited to complete an online survey by the end of 2021. Thirteen experts had previously answered the same questions.

Outcome measurements and statistical analysis

The submitted answers from 214 ISUP members, 191 EAU members, and 13 experts were analyzed.

Results and limitations

Currently, 53% use only the WHO2004 system and 40% use both systems. According to most respondents, PUNLMP is a rare diagnosis with management similar to Ta-LG carcinoma. The majority (72%) would consider reverting back to WHO1973 if grading criteria were more detailed. Separate reporting of WHO1973-G3 within WHO2004-HG would influence clinical decisions for Ta and/or T1 tumors according the majority (55%). Most respondents preferred a two-tier (41%) or a three-tier (41%) grading system. The current WHO2004 grading system is supported by a minority (20%), whereas nearly half (48%) supported a hybrid three- or four-tier grading system composed of both WHO1973 and WHO2004. The survey results of the experts were comparable with ISUP and EAU respondents.

Conclusions

Both the WHO1973 and the WHO2004 grading system are still widely used. Even though opinions on the future of bladder cancer grading were strongly divided, there was limited support for WHO1973 and WHO2004 in their current formats, while the hybrid (three-tier) grading system with LG, HG-G2, and HG-G3 as categories could be considered the most promising alternative.

Patient summary

Grading of non-muscle-invasive bladder cancer (NMIBC) is a matter of ongoing debate and lacks international consensus. We surveyed urologists and pathologists of European Association of Urology and International Society of Urological Pathology on their preferences regarding NMIBC grading to generate a multidisciplinary dialogue. Both the "old" World Health Organization (WHO) 1973 and the "new" WHO2004 grading schemes are still used widely. However, continuation of both the WHO1973 and the WHO2004 system showed limited support, while a hybrid grading system composed of both the WHO1973 and the WHO2004 classification system may be considered a promising alternative.

Metastatic solid tumours to the penis: a clinicopathologic evaluation of 109 cases from an international collaboration

AIMS

To elucidate the spectrum of metastatic tumours to the penis and their clinicopathologic features.

METHODS

The databases and files of 22 pathology departments from eight countries on three continents were queried to identify metastatic solid tumours of the penis and to characterize their clinical and pathologic features.

RESULTS

We compiled a series of 109 cases of metastatic solid tumours that secondarily involved the penis. The mean patient age at diagnosis was 71 years (range, 7-94 years). Clinical presentation commonly included a penile nodule/mass (48/95; 51%) and localised pain (14/95; 15%). A prior history of malignancy was known in 92/104 (89%) patients. Diagnosis was made mainly on biopsy (82/109; 75%), or penectomy (21/109; 19%) specimens. The most common penile locations were the glans (45/98; 46%) and corpus cavernosum (39/98; 39%). The most frequent histologic type was adenocarcinoma (56%). Most primary carcinomas originated in the genitourinary (76/108; 70%) and gastrointestinal (20/108; 18%) tracts, including prostate (38/108; 35%), urinary bladder (27/108; 25%), and colon/rectum (18/108; 17%). Concurrent or prior extrapenile metastases were identified in 50/78 (64%) patients. Clinical follow-up (mean 22 months, range 0-171 months) was available for 87/109 (80%) patients, of whom 46 (53%) died of disease.

CONCLUSION

This is the largest study to date of metastatic solid tumours secondarily involving the penis. The most frequent primaries originated from the genitourinary and gastrointestinal tracts. Metastatic penile tumours usually presented with penile nodules/masses and pain, and they often occurred in the setting of advanced metastatic disease, portending poor clinical outcomes.

Abstract 80: Change in B cell lymphocyte expression from the pre- to post-malignant prostate predicts disease aggressiveness

Background: Inflammatory cells such as tumor infiltrating lymphocytes (comprising T and B cells) are often present in prostate tissue undergoing tumorigenesis but their role in disease progression is unclear. The current study aims to characterize the expression dynamics of CD3, CD4 and CD20 lymphocytes from the pre- to post-malignant prostate environment and the association of these dynamics with aggressive prostate cancer.

Methods: The study sample included 72 prostate cancer cases (44 whites and 28 African American) that underwent surgery as their primary treatment and had a benign prostate biopsy at least one year before diagnosis and were followed for biochemical recurrence (BCR). Counts of CD3-, CD4- and CD20-positive lymphocytes were quantified by immunohistochemistry using an automated multi-image processing procedure in pre-malignant benign biopsy (BB), tumor-adjacent benign (TAB) and malignant tumor glandular (MTG) regions of prostatectomy. A cox proportional hazards model was used to estimate the hazard ratio (HR) of time to BCR associated with inflammatory marker count in different regions of the prostate. Clustering was performed to identify similar trends of expression changes of CD3, CD4 and CD20 between the regions - BB, TAG and MTG using Time-series Anytime Density Peaks Clustering (TADPole).

Results: The risk of BCR was significantly reduced in men who had an elevated CD20 count in the TAG (HR=0.80, p=0.01) after adjusting for race, age at diagnosis, PSA at the time of benign biopsy and the Gleason grade group. CD3 and CD4 counts in the prostate regions did not show any significant association to BCR. TADPole identified four main different patterns of CD20 expression changes across the BB-TAB-MTG regions namely 1) minimal to no change in expression between the regions (n=45 pairs); 2) high expression in BB/no expression in TAG/higher expression in MTG (n=3 pairs); 3) high expression in BB/higher expression in TAG/no expression in MTG (n=8 pairs); 4) no expression in BB/higher expression in TAG compared to MTG (n=16 pairs). In comparison to the reference group (Cluster 1), Cluster 4 was at 3.5 times higher risk of BCR with an adjusted HR of 3.5 (p=0.0184).

Conclusion: Elevated CD20 expression in TAG was associated with less aggressive disease. Furthermore, cases that had CD20 expression highest in their benign prostate adjacent to tumor preceded by absence of CD20 expression in their pre-malignant benign prostate had the most aggressive disease course. Further studies are warranted to understand how CD20 lymphocyte dynamic changes influence prostate tumorigenesis.

Citation Format: Sudha M. Sadasivan, Yalei Chen, Nilesh S. Gupta, Ryan Sanii, Kevin R. Bobbitt, Dhananjay A. Chitale, Sean R. Williamson, Andrew G. Rundle, Deliang Tang, Benjamin A. Rybicki. Change in B cell lymphocyte expression from the pre- to post-malignant prostate predicts disease aggressiveness [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 80.

Clear cell renal cell carcinoma with focal psammomatous calcifications: a rare occurrence mimicking translocation carcinoma

AIMS

Renal cell carcinoma (RCC) with clear cells and psammoma-like calcifications would often raise suspicion for MITF family translocation RCC. However, we have rarely encountered tumours consistent with clear cell RCC that contain focal psammomatous calcifications.

METHODS AND RESULTS

We identified clear cell RCCs with psammomatous calcifications from multiple institutions and performed immunohistochemistry and fluorescence and RNA in-situ hybridisation (FISH and RNA ISH). Twenty-one tumours were identified: 12 men, nine women, aged 45-83 years. Tumour size was 2.3-14.0 cm (median = 6.75 cm). Nucleolar grade was 3 (n = 14), 2 (n = 4) or 4 (n = 3). In addition to clear cell pattern, morphology included eosinophilic (n = 12), syncytial giant cell (n = 4), rhabdoid (n = 2), branched glandular (n = 1), early spindle cell (n = 1) and poorly differentiated components (n = 1). Labelling for CA9 was usually 80-100% of the tumour cells (n = 17 of 21), but was sometimes decreased in areas of eosinophilic cells (n = 4). All (19 of 19) were positive for CD10. Most (19 of 20) were positive for AMACR (variable staining = 20-100%). Staining was negative for keratin 7, although four showed rare positive cells (four of 20). Results were negative for cathepsin K (none of 19), melan A (none of 17), HMB45 (none of 17), TFE3 (none of 5), TRIM63 RNA ISH (none of 13), and TFE3 (none of 19) and TFEB rearrangements (none of 12). Seven of 19 (37%) showed chromosome 3p deletion. One (one of 19) showed trisomy 7 and 17 without papillary features.

CONCLUSIONS

Psammomatous calcifications in RCC with a clear cell pattern suggests a diagnosis of MITF family translocation RCC; however, psammomatous calcifications can rarely be found in true clear cell RCC.

Convolutional Neural Network Quantification of Gleason Pattern 4 and Association with Biochemical Recurrence in Intermediate Grade Prostate Tumors

Differential classification of prostate cancer (CaP) grade group (GG) 2 and 3 tumors remains challenging, likely due to the subjective quantification of percentage of Gleason pattern 4 (%GP4). Artificial intelligence assessment of %GP4 may improve its accuracy and reproducibility and provide information for prognosis prediction. To investigate this potential, a convolutional neural network (CNN) model was trained to objectively identify and quantify Gleason pattern (GP) 3 and 4 areas, estimate %GP4, and assess whether CNN-assessed %GP4 is associated with biochemical recurrence (BCR) risk in intermediate risk GG 2 and 3 tumors. The study was conducted in a radical prostatectomy cohort (1999-2012) of African American men from the Henry Ford Health System (Detroit, Michigan). A CNN model that could discriminate four tissue types (stroma, benign glands, GP3 glands, and GP4 glands) was developed using histopathologic images containing GG 1 (n=45) and 4 (n=20) tumor foci. The CNN model was applied to GG 2 (n=153) and 3 (n=62) for %GP4 estimation, and Cox proportional hazard modeling was used to assess the association of %GP4 and BCR, accounting for other clinicopathologic features including GG. The CNN model achieved an overall accuracy of 86% in distinguishing the four tissue types. Further, CNN-assessed %GP4 was significantly higher in GG 3 compared with GG 2 tumors (p=7.2*10^-11). %GP4 was associated with an increased risk of BCR (adjusted HR=1.09 per 10% increase in %GP4, p=0.010) in GG 2 and 3 tumors. Within GG 2 tumors specifically, %GP4 was more strongly associated with BCR (adjusted HR=1.12, p=0.006). Our findings demonstrate the feasibility of CNN-assessed %GP4 estimation, which is associated with BCR risk. This objective approach could be added to the standard pathological assessment for patients with GG 2 and 3 tumors and act as a surrogate for specialist genitourinary pathologist evaluation when such consultation is not available.

Low-grade oncocytic tumour of the kidney is characterised by genetic alterations of TSC1, TSC2, MTOR or PIK3CA and consistent GATA3 positivity

Low-grade oncocytic tumour (LOT) of the kidney has recently emerged as a potential novel tumour type. Despite similarity to oncocytoma or eosinophilic chromophobe renal cell carcinoma, it shows diffuse keratin 7 immunohistochemistry (IHC) and negative KIT (CD117), which differs from both. We aimed to identify the molecular characteristics of these tumours. Seventeen tumours (one male, 16 female, nine previously published) fitting the original description of this entity (solid eosinophilic cell morphology, often with areas of tumour cells loosely stretched in oedematous stroma, and the above IHC features) were analysed with a next-generation sequencing panel of 324 cancer-associated genes from formalin-fixed, paraffin-embedded tissue. All tumours harboured at least one alteration in either TSC1 (n = 7, 41%), TSC2 (n = 2, 12%), MTOR (n = 5, 29%) or PIK3CA (n = 4, 24%). Four tumours harboured a second alteration, including two NF2, one each in conjunction with MTOR and TSC2 alterations, one PTEN with TSC1 alteration and one tumour with both MTOR and TSC1 alterations. No other renal cancer-related or recurring gene alterations were identified. In addition to the previously described IHC findings, 16 of 16 were positive for GATA3. Eleven patients with follow-up had no metastases or recurrent tumours. Recurrent tuberous sclerosis/MTOR pathway gene alterations in LOT support its consideration as a distinct morphological, immunohistochemical and genetic entity. PIK3CA is another pathway member that may be altered in these tumours. Further study will be necessary to determine whether tumour behaviour or syndromic associations differ from those of oncocytoma and chromophobe carcinoma, warranting different clinical consideration.

Characterization of protein S-(2-succino)-cysteine (2SC) succination as a biomarker for fumarate hydratase-deficient renal cell carcinoma

Fumarate hydratase (FH)-deficient renal cell carcinoma (RCC) is an aggressive, rare genetic disease affecting the kidney and other organ systems. We constructed a specialized multi-institutional cohort of 20 primary FH-deficient RCC cases with aims of characterizing a new commercially available antibody, S-(2-succino)-cysteine (2SC). Herein, we present our findings on the biomarker characterization and performance of 2SC expression by immunohistochemistry (IHC) in FH-deficient RCC and other common and rare RCC subtypes. Morphological assessment revealed characteristic cytomorphologic features and a majority (55%) of FH-deficient RCC had mixed architectural growth patterns. We observed predominantly diffuse and strong cytoplasmic staining with limited nuclear positivity for 2SC staining on IHC. Receiver operating characteristic curves (ROC) for 2SC identified the threshold IHC score (cutoff) as 90, with the sensitivity and specificity being 100% and 91%, respectively. The findings of the present study along with the prior evidence in literature encourage utilization of 2SC as a positive marker along with the loss of FH expression by anti-FH IHC staining as a negative marker, in clinical and/or pathologic scenarios when considering FH-deficient RCC in the differential diagnosis. FH^-/2SC⁺ may serve as a comprehensive IHC panel in identifying such cases and excluding morphologically similar entities.

How New Developments Impact Diagnosis in Existing Renal Neoplasms

In recent years, several emerging diagnostic entities have been described in renal cell carcinoma (RCC). However, our understanding of well-known and established entities has also grown. Clear cell papillary RCC is now relabeled as a tumor rather than carcinoma in view of its nonaggressive behavior. Renal tumors with a predominantly infiltrative pattern are very important for recognition, as most of these have aggressive behavior, including fumarate hydratase-deficient RCC, SMARCB1-deficient medullary carcinoma, collecting duct carcinoma, urothelial carcinoma, and metastases from other cancers.

Recurrent KRAS mutations are early events in the development of papillary renal neoplasm with reverse polarity

We evaluated the clinicopathologic and molecular characteristics of mostly incidentally detected, small, papillary renal neoplasms with reverse polarity (PRNRP). The cohort comprised 50 PRNRP from 46 patients, divided into 2 groups. The clinically undetected (<5 mm) neoplasms (n = 34; 68%) had a median size of 1.1 mm (range 0.2-4.3 mm; mean 1.4 mm), and the clinically detected (≥5 mm) neoplasms (n = 16; 32%) which had a median size of 13 mm (range 9-30 mm; mean 16 mm). Neoplasms were positive for GATA3 (n = 47; 100%) and L1CAM (n = 34/38; 89%) and were negative for vimentin (n = 0/44; 0%) and, to a lesser extent, AMACR [(n = 12/46; 26%; weak = 9, weak/moderate = 3)]. KRAS mutations were found in 44% (n = 15/34) of the clinically undetected PRNRP and 88% of the clinically detected PRNRP (n = 14/16). The two clinically detected PRNRP with wild-type KRAS gene were markedly cystic and contained microscopic intracystic tumors. In the clinically undetected PRNRP, the detected KRAS mutations rate was higher in those measuring ≥1 mm vs <1 mm [n = 14/19 (74%) vs n = 1/15 (7%)]. Overall, the KRAS mutations were present in exon 2-codon 12: c.35 G > T (n = 21), c.34 G > T (n = 3), c.35 G > A (n = 2), c.34 G > C (n = 2) resulting in p.Gly12Val, p. Gly12Asp, p.Gly12Cys and p.Gly12Arg, respectively. One PRNRP had a G12A/V/D complex mutation. Twenty-six PRNRP were concurrently present with other tumors of different histologic subtypes in the ipsilateral kidney; molecular testing of 8 of the latter showed wild-type KRAS gene despite the presence of KRAS mutations in 5 concurrent PRNRP. On follow up, no adverse pathologic events were seen (range 1-160 months; mean 44 months). In conclusion, the presence of KRAS mutations in small, clinically undetected PRNRP provides a unique finding to this entity and supports its being an early event in the development of these neoplasms.

Nephrogenic Adenoma Intermixed With Urothelial Carcinoma

CONTEXT.—

Nephrogenic adenoma (NA) is a common urinary tract lesion typically associated with urothelial disruption, leading to implantation of shed renal tubular cells. NA may demonstrate a spectrum of architectural and cytologic features mimicking urothelial carcinoma (UC), adenocarcinoma (including clear cell adenocarcinoma and prostatic adenocarcinoma), and invasion. However, admixed UC and NA has not been described.

OBJECTIVE.—

To describe cases where the NA was intimately intermixed with UC, potentially mimicking variant differentiation or invasion.

DESIGN.—

In 3 health care systems we identified specimens of NA and UC intimately intermixed with each other where they could mimic a spectrum of one lesion. We assessed patterns of NA and clinical implications of misdiagnosing NA as glandular differentiation of UC.

RESULTS.—

There were 4 women and 29 men (median age, 72 years; range, 31-89 years). Twenty-four patients had transurethral resections, 3 had biopsies, and 6 had major resections. Fourteen had noninvasive high-grade papillary UC, 6 had carcinoma in situ, and 11 had invasive high-grade UC, and in 2 patients, NA developed in a papillary urothelial neoplasm with extensive denudation. Three patients had fibromyxoid NA infiltrated by invasive UC. Classical NA (n = 30) had tubulopapillary (n = 18), pure tubular (n = 7), or pure papillary architecture (n = 5). In 1 lesion, NA was present in muscularis propria, and 2 involved adventitia. NA could have been misdiagnosed as invasion in 17 of 22 (77%) noninvasive tumors, or higher stage in 19 of 33 (58%).

CONCLUSIONS.—

NA can be intermingled with high-grade UC, expanding the spectrum of entities that must be considered in the differential diagnosis, as it may mimic glandular or tubular differentiation, invasion, and a higher stage of disease. Misinterpretation of NA in such a setting may incorrectly convey a more aggressive biological potential of cancer to clinicians.

Prostatic Malakoplakia: Clinicopathologic Assessment of a Multi-institutional Series of 49 Patients

Prostatic MP is rare, with only case reports and small series (<5 patients) available in the literature. In this study we analyzed an international multi-institutional series of 49 patients with prostatic MP to better define its clinicopathologic features. The median age was 67 years, and the median serum PSA was 7.5 ng/mL. MP was clinically manifest in most cases (28/45 patients with data available, 62%). Of 43 patients with detailed clinical history available, 21 (49%) had concurrent or metachronous malignancies (including prostate cancer). Diabetes or insulin resistance was present in 11 patients (26%). Additionally, 3 patients had a history of solid organ transplantation and 1 had HIV. Of note, 6/34 patients (18%) without concurrent prostate cancer had an abnormal digital rectal examination or PIRADS ≥ 4 lesions on MRI. The initial diagnosis was made on core biopsies (25/49, 51%), transurethral resection specimens (12/49, 24%), radical prostatectomies (10/49, 20%), Holmium-laser enucleation (1/49, 2%) and cystoprostatectomy (1/49, 2%). Tissue involvement was more commonly diffuse or multifocal (40/49, 82%). Von Kossa and Periodic acid-Schiff stains were positive in 35/38 (92%) and 26/27 lesions (96%), respectively. Of note, 2 cases were received in consultation by the authors with a preliminary diagnosis of mesenchymal tumor/tumor of the specialized prostatic stroma. In conclusion, the present study, which is the largest to date, suggests that prostatic MP often manifests with signs and symptoms that may mimic those of prostate cancer in a subset of patients. Moreover, MP may be found incidentally in patients with concurrent prostate cancer.

The Histologic Diversity of Chromophobe Renal Cell Carcinoma With Emphasis on Challenges Encountered in Daily Practice

Chromophobe renal cell carcinoma (ChRCC) is the third most common renal cell carcinoma in adults. The aim of this review is to provide a comprehensive overview highlighting the broad morphologic spectrum of ChRCC, and offer a practical approach for handling cases in daily practice. For the purpose of this review, we classify ChRCC subtypes as (1) classic, (2) eosinophilic, (3) sarcomatoid, and (4) other rare patterns. The concept of eosinophilic ChRCC has significantly evolved, yet it still is one of the major diagnostic challenges pathologists face in routine practice due to its morphologic overlap with renal oncocytoma. Rare patterns of ChRCC have been described over the last few decades, showing a wide histologic spectrum including those with adenomatoid microcystic pigmented, multicystic, neuroendocrine, small cell, and papillary features. ChRCC represents a heterogenous group of neoplasms, demonstrating varied but unique morphologic and genetic profiles. Although the field of ChRCC knowledge is still evolving, rare patterns can present diagnostic challenges if they are not known to pathologists and/or clinicians. Proper and generous tumor sampling along with careful histologic examination allow for recognition of these rare morphologies. The role of routine molecular testing appears to be limited. From a clinical management standpoint, the rare patterns of ChRCC seem to have no definite clinical implications at present and likely can be managed similarly to usual ChRCC. Finally, we will discuss distinctive novel/emerging renal neoplasms previously considered under the spectrum of ChRCC, low-grade oncocytic renal tumor and eosinophilic vacuolated tumor, with regard to their current significance and implications for future classification strategies.

Clear Cell Renal Cell Carcinoma with Immunotherapy Effect Mimicking Xanthogranulomatous Pyelonephritis

Renal cell carcinoma is now increasingly treated with checkpoint inhibitor therapy, predominantly in the metastatic setting or occasionally in the adjuvant setting; however, there is little published histopathology data demonstrating the post-therapy features of renal cell carcinoma tumor tissue. We report a middle-aged man, who was undergoing treatment with pembrolizumab for locally recurrent cutaneous basal cell carcinoma and was incidentally found to have a renal mass. Radical nephrectomy demonstrated a 5.0 cm renal mass with extensive xanthogranulomatous features, mimicking xanthogranulomatous pyelonephritis. However, rare clusters of cells demonstrated gland-like lumina, clear cytoplasm, and slightly increased atypia, suggesting scant residual renal cell carcinoma cells. Immunohistochemistry demonstrated focal positivity for pan-keratin and keratin 8/18, EMA, PAX8, CD10, and carbonic anhydrase 9 (CA9), supporting a diagnosis of renal cell carcinoma with extensive treatment response, to the point that it mimicked xanthogranulomatous pyelonephritis. This report demonstrates the histologic features of post-immunotherapy renal cell carcinoma, aiding pathologists in recognition of this phenomenon, which may be misdiagnosed as an inflammatory process, if immunotherapy was performed for other reasons.

Race Differences in Telomere Length in Benign Prostate Biopsies and Subsequent Risk of Prostate Cancer

BACKGROUND

Telomere shortening is linked to aging and may be associated with increased risk for cancer. Most cancer studies have used telomere length in leukocytes rather than in the target tissue of cancer origin.

METHODS

A case-control study of 524 case-control pairs with a benign prostate biopsy nested within a historical cohort of 10,478 men was conducted to determine whether premalignant prostate telomere length (assessed using a modified qRT-PCR) is associated with prostate cancer risk.

RESULTS

Telomere lengths in benign prostate biopsies of cases versus controls were similar (1.46 ± 0.38 vs. 1.45 ± 0.42; P = 0.49). African American (AA) men had significantly shorter telomeres compared with White men (1.51 ± 0.38 vs. 1.63 ± 0.39; P < 0.0001). In race-stratified analyses, increasing telomere length was more strongly associated with prostate cancer risk in White men, wherein those with telomere length in the highest quartile had 1.9-fold greater adjusted risk of prostate cancer compared with men with prostate telomere lengths in the lowest quartile [OR = 1.90; 95% confidence interval (CI) = 1.08-3.36]. Men in the highest telomere length quartile also had a greater risk of aggressive prostate cancer compared with men with telomere lengths in the lowest quartile (OR = 2.78; 95% CI = 1.25-6.19).

CONCLUSIONS

White men have longer telomeres in benign prostate tissue compared with AA men, and those with the longest telomeres may be at increased risk for prostate cancer, particularly the more aggressive form of the disease.

IMPACT

Race-specific telomere length measures may be an early biomarker of aggressive prostate cancer.

The Pathologic and Molecular Genetic Landscape of the Hereditary Renal Cancer Predisposition Syndromes

It is estimated that 5-8% of renal tumors are hereditary in nature with many inherited as autosomal dominant. These tumors carry a unique spectrum of pathologic and molecular alterations, the knowledge of which is expanding in the recent years. Indebted to this knowledge, many advances in treatment of these tumors have been achieved. In this review, we summarize the current understanding of the genetic renal neoplasia syndromes, the clinical and pathologic presentations, their molecular pathogenesis, the advances in therapeutic implications and targeted therapy.

Eosinophilic vacuolated tumor (EVT) of kidney demonstrates sporadic TSC/MTOR mutations: next-generation sequencing multi-institutional study of 19 cases

A distinct renal tumor has recently been described as "high-grade oncocytic renal tumor" and "sporadic renal cell carcinoma with eosinophilic and vacuolated cytoplasm". The Genitourinary Pathology Society (GUPS) consensus proposed a unifying name "eosinophilic vacuolated tumor" (EVT) for this emerging entity. In this multi-institutional study, we evaluated 19 EVTs, particularly their molecular features and mutation profile, using next-generation sequencing. All cases were sporadic and none of the patients had a tuberous sclerosis complex. There were 8 men and 11 women, with a mean age of 47 years (median 50; range 15-72 years). Average tumor size was 4.3 cm (median 3.8 cm; range 1.5-11.5 cm). All patients with available follow-up data (18/19) were alive and without evidence of disease recurrence or progression during the follow-up, ranging from 12 to 198 months (mean 56.3, median 41.5 months). The tumors were well circumscribed, but lacked a well-formed capsule, had nested to solid growth, focal tubular architecture, and showed ubiquitous, large intracytoplasmic vacuoles, round to oval nuclei, and prominent nucleoli. Immunohistochemically, cathepsin K, CD117, CD10, and antimitochondrial antigen were expressed in all cases. Other positive stains included: PAX8, AE1/AE3 and CK18. CK7 was typically restricted only to rare scattered cells. Vimentin, HMB45, melan-A, and TFE3 were negative in all cases. All tumors showed retained SDHB. All cases (19/19) showed non-overlapping mutations of the mTOR pathway genes: TSC1 (4), TSC2 (7), and MTOR (8); one case with MTOR mutation showed a coexistent RICTOR missense mutation. Low mutational rates were found in all samples (ranged from 0 to 6 mutations/Mbp). Microsatellite instability and copy number variations were not found in any of the 17 analyzable cases. EVT represents an emerging renal entity that shows a characteristic and readily identifiable morphology, consistent immunohistochemical profile, indolent behavior, and mutations in either TSC1, TSC2, or MTOR genes.

Papillary Renal Cell Carcinoma With Microcystic Architecture Is Strongly Associated With Extrarenal Invasion and Metastatic Disease

Papillary renal cell carcinoma (PRCC) is well-recognized as a morphologically and molecularly heterogenous group of kidney tumors with variable clinical behavior. Our goal was to analyze a unique histologic pattern of PRCC we have observed in routine practice to evaluate for potential clinical significance or distinct molecular signature. We identified 42 cases of PRCC showing a morphologically distinct architecture characterized by numerous epithelial-lined cysts containing the papillary tumor (herein called "microcysts"), which are typically separated by fibrous stroma. Of the initial 42 case test set with microcystic features, 23 (55%) were stage pT3a or higher. Most tumors had strong and diffuse cytoplasmic immunoreactivity for CK7 (93%, 37/40) and AMACR (100%, 40/40). Fumarate hydratase staining was retained in all cases tested (39/39). We performed next-generation sequencing on 15 of these cases with available tissue and identified chromosomal alterations commonly reported in historically "type 1" PRCC, notably multiple chromosomal gains, particularly of chromosomes 7 and 17, and MET alterations. However, alterations in pathways associated with more aggressive behavior (including SETD2, CDKN2A, and members of the NRF pathway) were also identified in 6 of 15 cases tested (40%). Given this molecular and immunophenotypic data, we subsequently reviewed an additional group of 60 consecutive pT2b-pT3 PRCCs to allow for comparisons between cases with and without microcysts, to assess for potential associations with other recently described histologic patterns (ie, "unfavorable architecture": micropapillary, solid, and hobnail), and to assess interobserver reproducibility for diagnosing architectural patterns and grade. Of the total combined 102 PRCCs, 67 (66%) had microcystic architecture within the intrarenal component but were commonly admixed with other patterns (39% had micropapillary, 31% solid, and 31% hobnail). Twenty-seven cases (26%) had metastatic disease, and 24 of these 27 (89%) had microcystic architecture in the intrarenal tumor. Within the pT3 subset, 21 of 22 cases with metastases (95%) had extrarenal invasion as either individual microcysts in renal sinus fat or aggregates of microcysts bulging beyond the confines of the capsule. Backward elimination and stepwise regression methods to detect features significantly associated with adverse outcome identified solid architecture (hazard ratio [HR]: 6.3; confidence interval [CI]: 2.1-18.8; P=0.001), hobnail architecture (HR: 5.3; CI: 1.7-16.7; P=0.004), and microcystic architecture at the tumor-stromal interface (HR: 4.2; CI: 1.1-16.7; P=0.036) as strongest. Of architectural patterns and grade, the microcystic pattern had a substantial interobserver agreement (κ score=0.795) that was highest among the 6 observers. In summary, PRCCs with microcystic architecture represents a subset of historically "type 1" PRCC with a predilection for morphologically distinctive extrarenal involvement and metastatic disease. Microcysts co-vary with other "unfavorable" architectural patterns also associated with higher risk for aggressive disease (ie, micropapillary, hobnail, and solid), but microcysts were more common and have superior interobserver reproducibility. These findings suggest that microcystic PRCC should be recognized as a potentially aggressive histologic pattern of growth in PRCC.

Nodular Maturation of the Testis: A Non-neoplastic Lesion of Boys That May Present as a Mass on Clinical and Ultrasound Examination

We have encountered a lesion of the pediatric testis, termed "nodular maturation," that clinically mimics a testicular neoplasm causing ultrasound abnormalities that may lead to surgical excision. To our knowledge, it has only been described anecdotally in textbooks without a series or description in the literature. We, therefore, report 8 cases in pediatric patients emphasizing the clinical presentation, ultrasound findings, histologic features, and clinical follow-up information. Patients ranged in age from 5 to 11 years (mean: 7.9 y). Precocious puberty was identified in 1 patient as isolated penile enlargement without other signs; another had a history of McCune-Albright syndrome, but did not have signs of precocious puberty; others had no clinical manifestations. All patients had testicular abnormalities on ultrasound; 6 had a discrete lesion and 2 showed diffuse testicular enlargement. In the 6 cases with available data, mean size of the lesion on ultrasound was 0.9 cm (range: 0.4 to 1.7 cm). In the 3 cases for which macroscopic descriptions were available, no gross abnormalities were noted in the testicular parenchyma, despite the ultrasound findings. Histologically, nodular maturation occurred as a zone of more mature testicular parenchyma having larger, lumen-bearing seminiferous tubules that contrasted with the smaller, immature cords of the remaining parenchyma. The mature tubules showed germ cell maturation (to the level of late spermatids/spermatozoa in 6 cases), mature Sertoli cells, and, in 4 cases, admixed nodules of mature Leydig cells. Of the 6 patients with available follow-up information, none developed a testicular neoplasm. Given its ability to cause a lesion on ultrasound leading to surgical intervention, pathologists, radiologists, and urologists should be aware of nodular maturation.

Immunohistochemistry for the diagnosis of renal epithelial neoplasms

Despite the increasing number of newly identified renal neoplasms, the diagnosis of renal cell carcinoma (RCC) can usually be reached with careful histologic examination and a limited immunohistochemical (IHC) panel. Clear cell, papillary, chromophobe RCC and oncocytoma account for more than 90% of renal neoplasia in adults, and sophisticated ancillary tools are usually unnecessary. Renal tumors with entity-defining genetic alterations may ultimately require molecular confirmation via cytogenetics or sequencing technologies, such as RCC with TFE3, TFEB, or ALK gene rearrangements, or TFEB amplified RCC. In fumarate hydratase-deficient and succinate dehydrogenase-deficient RCC, highly specific IHC markers can strongly suggest the diagnosis. In the metastatic setting, PAX8 and carbonic anhydrase 9 are among the most helpful markers for confirming RCC and clear cell type, respectively; however, caution should be exercised in the absence of a current or historical renal mass. In diagnostically challenging cases, such as renal eosinophilic tumors with low-grade nuclear features, or infiltrative high-grade tumors, careful examination coupled with a judicious panel of IHC markers usually resolves the diagnosis. This review offers concise algorithms for diagnosis of kidney neoplasia with the latest recognized, provisional, and emerging entities to daily pathology practice.

Mutation Profile Variability in the Primary Tumor and Multiple Pulmonary Metastases of Clear Cell Renal Cell Carcinoma. A Review of the Literature and Analysis of Four Metastatic Cases

(1) Background: There are limited data concerning inter-tumoral and inter-metastatic heterogeneity in clear cell renal cell carcinoma (CCRCC). The aim of our study was to review published data and to examine mutation profile variability in primary and multiple pulmonary metastases (PMs) in our cohort of four patients with metastatic CCRCC. (2) Methods: Four patients were enrolled in this study. The clinical characteristics, types of surgeries, histopathologic results, immunohistochemical and genetic evaluations of corresponding primary tumor and PMs, and follow-up data were recorded. (3) Results: In our series, the most commonly mutated genes were those in the canonically dysregulated VHL pathway, which were detected in both primary tumors and corresponding metastasis. There were genetic profile differences between primary and metastatic tumors, as well as among particular metastases in one patient. (4) Conclusions: CCRCC shows heterogeneity between the primary tumor and its metastasis. Such mutational changes may be responsible for suboptimal treatment outcomes in targeted therapy settings.

Reappraisal of HER2 Amplification in High-Grade Urothelial Carcinoma Based on 2018 ASCO/CAP Clinical Practice Guidelines

OBJECTIVES

To examine and compare human epidermal growth factor receptor 2 (HER2) amplification status in high-grade urothelial carcinoma (HGUCa), using both 2013 and 2018 HER2 reporting guidelines for breast carcinoma from the American Society of Clinical Oncology (ASCO)/College of American Pathologists (CAP).

METHODS

HER2 status by fluorescence in situ hybridization (FISH) assay in 78 cases of HGUCa was compared using 2013 and 2018 HER2 reporting guidelines.

RESULTS

HER2 amplification was observed in 22 (28.2%) of 78 tumors, of which 17 were in group 1, 1 in group 2, and 2 each in groups 3 and 4 (FISH assay, 2018). The remaining 14 HER2-amplified tumors (FISH assay, 2013) became negative, falling into group 2 (FISH assay, 2018) and were either negative or equivocal on immunohistochemistry (IHC, 2018). All FISH-negative tumors (n = 37) using 2013 criteria remained negative (group 5, 2018). FISH-equivocal tumors (2013) were further categorized into HER2 amplified (n = 1) and HER2 negative (n = 4) (2018). Overall, 20 (25.6%) tumors had discordant HER2 FISH results (2018 vs 2013).

CONCLUSIONS

Implementing 2018 guidelines, HER2 amplification decreased from 36 to 22 cases. The group with a HER2/CEP17 ratio of 2 or more and average HER2 copy number less than 4 (group 2) were predominantly negative by IHC, suggesting a biologically distinct group of HGUCa that is different from HER2-amplified tumors, which may not respond to HER2-targeted therapy.

EWSR1-PATZ1 fusion renal cell carcinoma: a recurrent gene fusion characterizing thyroid-like follicular renal cell carcinoma

Thyroid-like follicular renal cell carcinoma is an uncommon kidney tumor with no distinct molecular alteration described to date. This cohort of eight women with mean and median ages of 45 and 46 years, respectively (range 19-65 years), had unencapsulated, well-circumscribed tumors composed of tightly packed anastomosing follicle-like cysts filled with eosinophilic colloid-like material and lined by cuboidal cells with high nuclear to cytoplasmic ratios, oval to elongated nuclei with perpendicular arrangement toward the lumens, and prominent nuclear overlapping. The stroma between these was minimal with the exception of two tumors. Calcifications and necrosis were absent. Immunohistochemically, the tumors were positive for KRT19 (7/7), PAX8 (5/5), cyclin D1 (6/6), KRT7 (5/7), and AMACR (1/5; focal, weak), and were negative for WT1, TTF1 (transcription termination factor-1), and thyroglobulin. In three of three tumors tested molecularly, EWSR1-PATZ1 fusion was identified by RNA sequencing and confirmed by RT-PCR and Sanger sequencing. Over a follow-up period of 1-7 years, no evidence of recurrence or metastasis has been detected. The EWSR1-PATZ1 fusion has been recognized as a recurrent alteration in a subset of round to spindle cell sarcomas with EWSR1-non-ETS fusions (EWSR1-PATZ1 sarcoma) and in several central nervous system tumors. The finding of an EWSR1-PATZ1 fusion in all three of the thyroid-like follicular renal cell carcinomas for which sufficient tissue was available for genomic profiling provides the first distinct molecular abnormality in thyroid-like follicular renal cell carcinomas, supporting its designation as a distinct diagnostic entity.

Renal Oncocytoma With Both Lymphovascular Invasion and Prominent Intracytoplasmic Vacuole-Like Spaces: A Case Report and Review of the Literature

Here we report a case of renal oncocytoma in a 68 year-old male. The diagnosis was initially made on a needle biopsy 6 years prior to the partial nephrectomy. The case is unique that in addition to the gross and microscopic features commonly seen in renal oncocytomas, both lymphovascular invasion and prominent intracytoplasmic vacuole-like spaces are also present in this tumor. Although vascular invasion is increasingly recognized as compatible with renal oncocytoma, intracytoplasmic vacuoles are a rare and unusual finding that may lead to diagnostic difficulty. The diagnosis of renal oncocytoma was confirmed after immunohistochemistry was performed to argue against succinate dehydrogenase deficient renal cell carcinoma (RCC) and chromophobe RCC. This case highlights the importance for practicing pathologists to recognize the rare co-occurrence of lymphovascular invasion and large intracytoplasmic vacuole-like spaces in renal oncocytoma. Other differential diagnoses may include emerging renal tumor entities, such as the recently-proposed eosinophilic vacuolated tumor.

Diagnosis of "cribriform" prostatic adenocarcinoma: an interobserver reproducibility study among urologic pathologists with recommendations

Accurate diagnosis of cribriform Gleason pattern 4 (CrP4) prostate adenocarcinoma (PCa) is important due to its independent association with adverse clinical outcomes and as a growing body of evidence suggests that it impacts clinical decision making in PCa management. To identify reproducible features for diagnosis of CrP4, we assessed interobserver agreement among 27 experienced urologic pathologists of 60 digital images from 44 radical prostatectomies (RP) that represented a broad spectrum of potential CrP4. The following morphologic features were correlated with the consensus diagnosis (defined as 75% agreement) for each image: partial vs. transluminal glandular bridging, intraglandular stroma, <12 vs. ≥12 lumina, well vs. poorly formed lumina, mucin (mucinous fibroplasia, extravasation, or extracellular pool), size (compared to benign glands and number of lumina), number of attachments with gland border by tumor cells forming a "glomeruloid-like" pattern, a clear luminal space along the periphery of gland occupying <50% of glandular circumference, central nerve, dense (cell mass occupying >50% of luminal space) vs. loose, and regular vs. irregular contour. Interobserver reproducibility for the overall diagnostic agreement was fair (k=0.40). Large CrP4 had better agreement (k=0.49) compared to small CrP4 (k=0.40). Transluminal bridging, dense cellular proliferation, a clear luminal space along the periphery of gland occupying <50% of gland circumference, lack of intraglandular mucin, and lack of contact between the majority of intraglandular cells with stroma were significantly associated with consensus for CrP4. In contrast, partial bridging, majority of intraglandular cells in contact with stroma, mucinous fibroplasia, only one attachment to the gland border by tumor cells forming a "glomeruloid-like" pattern, and a clear luminal space along the periphery of gland accounting for >50% of the glandular circumference were associated with consensus against CrP4. In summary, we identified reproducible morphological features for and against CrP4 diagnosis, which could be used to refine and standardize the diagnostic criteria for CrP4.

A multi-center retrospective cohort study defines the spectrum of kidney pathology in Coronavirus 2019 Disease (COVID-19)

Kidney failure is common in patients with Coronavirus Disease-19 (COVID-19) resulting in increased morbidity and mortality. In an international collaboration, 284 kidney biopsies were evaluated to improve understanding of kidney disease in COVID-19. Diagnoses were compared to five years of 63,575 native biopsies prior to the pandemic and 13,955 allograft biopsies to identify diseases increased in patients with COVID-19. Genotyping for APOL1 G1 and G2 alleles was performed in 107 African American and Hispanic patients. Immunohistochemistry for SARS-CoV-2 was utilized to assess direct viral infection in 273 cases along with clinical information at the time of biopsy. The leading indication for native biopsy was acute kidney injury (45.4%), followed by proteinuria with or without concurrent acute kidney injury (42.6%). There were more African American patients (44.6%) than patients of other ethnicities. The most common diagnosis in native biopsies was collapsing glomerulopathy (25.8%) which associated with high-risk APOL1 genotypes in 91.7% of cases. Compared to the five-year biopsy database, the frequency of myoglobin cast nephropathy and proliferative glomerulonephritis with monoclonal IgG deposits was also increased in patients with COVID-19 (3.3% and 1.7%, respectively), while there was a reduced frequency of chronic conditions (including diabetes mellitus, IgA nephropathy, and arterionephrosclerosis) as the primary diagnosis. In transplants, the leading indication was acute kidney injury (86.4%), for which rejection was the predominant diagnosis (61.4%). Direct SARS-CoV-2 viral infection was not identified. Thus, our multi-center large case series identified kidney diseases that disproportionately affect patients with COVID-19, demonstrated a high frequency of APOL1 high-risk genotypes within this group, with no evidence of direct viral infection within the kidney.

Racial differences in the systemic inflammatory response to prostate cancer

Systemic inflammation may increase risk for prostate cancer progression, but the role it plays in prostate cancer susceptibility is unknown. From a cohort of over 10,000 men who had either a prostate biopsy or transurethral resection that yielded a benign finding, we analyzed 517 incident prostate cancer cases identified during follow-up and 373 controls with one or more white blood cell tests during a follow-up period between one and 18 years. Multilevel, multivariable longitudinal models were fit to two measures of systemic inflammation, neutrophil-to-lymphocyte ratio (NLR) and monocyte-to-lymphocyte ratio (MLR), to determine NLR and MLR trajectories associated with increased risk for prostate cancer. For both measures, we found no significant differences in the trajectories by case/control status, however in modeling NLR trajectories there was a significant interaction between race (white or Black and case-control status. In race specific models, NLR and MLR values were consistently higher over time among white controls than white cases while case-control differences in NLR and MLR trajectories were not apparent among Black men. When cases were classified as aggressive as compared to non-aggressive, the case-control differences in NLR and MLR values over time among white men were most apparent for non-aggressive cases. For NLR among white men, significant case-control differences were observed for the entire duration of observation for men who had inflammation in their initial prostate specimen. It is possible that, among white men, monitoring of NLR and MLR trajectories after an initial negative biopsy may be useful in monitoring prostate cancer risk.

Abstract 750: Race differences in telomere length in benign prostate and subsequent risk of prostate cancer

Telomere shortening is linked to aging and thought to be associated with increased risk for cancer. Most cancer studies have used leukocyte telomere length as a surrogate measure for telomere length with few focused upon telomeres in the target tissue of cancer origin. To determine whether telomere length in pre-malignant prostate tissue is associated with subsequent prostate cancer risk, we conducted a case-control study of 530 case-control pairs matched on date, age at cohort entry, and race nested within a historical cohort of 10,478 men with a benign prostate biopsy. Overall mean telomere length assessed using modified quantitative real-time PCR was not different in benign prostate biopsies of prostate cancer cases vs. matched controls (1.65 ± 0.35 vs. 1.64 ± 0.39; p=0.41). However, race was significantly associated with telomere length with African American (AA) men having shorter telomeres in benign prostate biopsy compared with white men (1.59 ± 0.37 vs. 1.70 ± 0.37; p&lt;0.0001). In race-stratified analyses, telomere length only showed a suggestive association with prostate cancer risk in white men, wherein those with telomere length in the highest quartile had 1.5-fold greater risk of prostate cancer compared to men with prostate telomere lengths in the lowest quartile (OR=1.56; 95% CI = 0.89 - 2.73 ). In addition, white men in the highest prostate telomere length quartile had almost three-fold greater risk of aggressive prostate cancer, defined as Gleason group 3 and above, tumor stage 3 or above or PSA 20 ng/ml or higher , compared with men with telomere lengths in the lowest quartile (OR=2.73; 95% CI =1.05 - 7.15). In summary, white men have longer telomeres in benign prostate tissue compared with AA men, and those with the longest telomeres may be at increased risk for prostate cancer, particularly the more aggressive form of the disease.

Citation Format: Benjamin A. Rybicki, Sudha M. Sadasivan, Yalei Chen, Ian Loveless, Nilesh S. Gupta, Dhananjay A. Chitale, Sean R. Williamson, Andrew G. Rundle, Deliang Tang. Race differences in telomere length in benign prostate and subsequent risk of prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 750.

The interplay of growth differentiation factor 15 (GDF15) expression and M2 macrophages during prostate carcinogenesis

M2 (tumor-supportive) macrophages may upregulate growth differentiation factor 15 (GDF15), which is highly expressed in prostate tumors, but the combined utility of these markers as prognostic biomarkers are unclear. We retrospectively studied 90 prostate cancer cases that underwent radical prostatectomy as their primary treatment and were followed for biochemical recurrence (BCR). These cases also had a benign prostate biopsy at least 1 year or more before their prostate cancer surgery. Using computer algorithms to analyze digitalized immunohistochemically stained slides, GDF15 expression and the presence of M2 macrophages based on the relative density of CD204- and CD68-positive macrophages were measured in prostate: (i) benign biopsy, (ii) cancer and (iii) tumor-adjacent benign (TAB) tissue. Both M2 macrophages (P = 0.0004) and GDF15 (P < 0.0001) showed significant inter-region expression differences. Based on a Cox proportional hazards model, GDF15 expression was not associated with BCR but, in men where GDF15 expression differences between cancer and TAB were highest, the risk of BCR was significantly reduced (hazard ratio = 0.26; 95% confidence interval = 0.09-0.94). In addition, cases with high levels of M2 macrophages in prostate cancer had almost a 5-fold increased risk of BCR (P = 0.01). Expression of GDF15 in prostate TAB was associated with M2 macrophage levels in both prostate cancer and TAB and appeared to moderate M2-macrophage-associated BCR risk. In summary, the relationship of GDF15 expression and CD204-positive M2 macrophage levels is different in a prostate tumor environment compared with an earlier benign biopsy and, collectively, these markers may predict aggressive disease.