Immunohistochemistry as an adjunct in the differential diagnosis of radiation-induced atypia versus urothelial carcinoma in situ of the bladder: a study of 45 cases

Immunohistochemical Evaluation of Renal Biopsy with Anti-PD1 and p53 to Solve the Dilemma between Platinum- and Pembrolizumab-Induced AKI: Case Report and Review

Introduction: The combination therapy of platinum and pembrolizumab looks like a promising treatment in advanced non-small-cell lung cancer. However, both platinum-based chemotherapy and pembrolizumab can lead to AKI. AKI can occur due to acute tubular necrosis or interstitial nephritis. It is essential to identify the drug responsible for renal damage. For this purpose, we used new immunohistochemistry markers (p53 and anti-PD1 analysis). Case Description: A 77-year-old female patient with advanced non-small-cell lung cancer received the PD-1 inhibitor pembrolizumab and platinum-based chemotherapy carboplatin. The patient, after 60 days, experienced AKI. A kidney biopsy was performed, and two new immunohistochemical techniques for p53 (experimental markers of ATN from platinum) and anti-PDL1 (experimental markers of PD-1 inhibitors nephritis) were employed. Renal biopsies revealed severe tubular damage. No infiltration was detected, and the immunohistochemical assessment of PDL-1 was negative. The expression of p53 was positive. The renal biopsy suggested platinum-induced acute tubular necrosis. After discontinuing steroids and reducing carboplatin, the patient continued with pembrolizumab, and their renal function returned to normal within two months. Discussion: Combining checkpoint inhibitors and platinum-based therapies may result in AKI. The standard method of examining kidney tissue may not provide sufficient information about the effects of these drugs on the kidneys. To address this issue, we recommend incorporating an assessment of the analysis of the expression of PDL1 and p53. This personalized approach will help identify the best treatment option for the patient while ensuring the best possible cancer treatment plan.

Diagnostic Roles of Immunohistochemical Markers CK20, CD44, AMACR, and p53 in Urothelial Carcinoma In Situ

Background and Objectives: This study aimed to evaluate the diagnostic roles of various immunohistochemical (IHC) markers in urothelial carcinoma in situ (uCIS) through a meta-analysis and review of diagnostic test accuracy. Materials and Methods: The IHC markers CK20, CD44, AMACR, and p53 were evaluated in the present study. We analyzed the expression rates of the IHC markers and compared their diagnostic accuracies. Results: The estimated expression rates were 0.803 (95% confidence interval [CI]: 0.726-0.862), 0.142 (95% CI: 0.033-0.449), 0.824 (95% CI: 0.720-0.895), and 0.600 (95% CI: 0.510-0.683) for CK20, CD44, AMACR, and p53, respectively. In the comparison between uCIS and reactive/normal urothelium, the expression of CK20, AMACR, and p53 in uCIS was significantly higher than in reactive/normal urothelium. CD44 showed significantly lower expression in uCIS than in the reactive/normal urothelium. Among the markers, AMACR had the highest sensitivity, specificity, and diagnostic odds ratio. The AUC on SROC was the highest for CK20. Conclusions: In conclusion, IHC markers, such as CK20, CD44, AMACR, and p53, can be useful in differentiating uCIS from reactive/normal urothelium.

Urothelial carcinoma in situ with "overriding" features can evade detection by mimicking umbrella cells

Urothelial carcinoma in situ (uCIS) is typically recognized by overtly malignant cells with characteristic nuclear features; multiple histologic patterns have been described. A rare "overriding" pattern, in which uCIS tumor cells extend on top of normal urothelium, has previously been mentioned in the literature, but not well-described. Herein, we report three cases of uCIS with "overriding" features. Detailed morphologic evaluation revealed somewhat subtle cytologic atypia: variably enlarged hyperchromatic nuclei, scattered mitotic figures but with abundant cytoplasm and limited to superficial urothelium. Immunohistochemical (IHC) analysis showed a distinctive diffuse positive aberrant p53 pattern, limited to the atypical surface urothelial cells; these cells were also CK20+, CD44-, and Ki67 increased. In two cases, there was a history of urothelial carcinoma and adjacent conventional uCIS. In the third case, the "overriding" pattern was the first presentation of urothelial carcinoma; therefore next generation sequencing molecular testing was also performed, revealing pathogenic mutations in TERTp, TP53, and CDKN1a to further support neoplasia. Notably, the "overriding" pattern mimicked umbrella cells, which normally line surface urothelium, can have abundant cytoplasm, more variation in nuclear and cell size and shape, and show CK20+ IHC. We therefore also evaluated umbrella cell IHC patterns in adjacent benign/reactive urothelium, which showed CK20+, CD44-, p53 wild-type and very low Ki67 (3/3). We also reviewed 32 cases of normal/reactive urothelium: all showed p53 wild-type IHC in the umbrella cell layer (32/32). In conclusion, caution is warranted to avoid overdiagnosis of usual umbrella cells as CIS; however, "overriding" uCIS should be recognized, may have morphologic features that fall short of the diagnostic threshold of conventional CIS, and requires further study.

Precursors of urinary bladder cancer: molecular alterations and biomarkers

Clinical surveillance and follow-up of patients diagnosed with or at risk for urinary bladder cancers represent long-term, invasive, and costly processes for which supplemental biomarker information could help provide objective, personalized risk assessment. In particular, there are several precursors and possible precursors to urinary bladder cancer for which clinical behavior is heterogenous and interobserver variability in histopathologic diagnosis make it difficult to standardize management. This review seeks to highlight these precursor lesions from a diagnostic perspective (including flat urothelial lesions, papillary urothelial lesions, squamous lesions, and glandular lesions) and qualify known multiomic biomarkers that may help explain their behavior, predict patient risk, and acknowledge the nuance inherent to the question of whether these lesions are "benign" or "preneoplastic."

A systematic review and meta-analysis of CK20, CD44, Ki67 and p53 as immunohistochemical markers in bladder carcinoma in situ

BACKGROUND

Urothelial dysplasia and carcinoma in situ (CIS) are related to recurrence and progression of urothelial carcinoma. Differentiating CIS and dysplasia from reactive atypia is often difficult based only on histological features. The integration of histological findings with immunohistochemistry is used in routine practice to make a diagnosis of CIS and, for this purpose, the immunohistochemical markers CK20, CD44, Ki67 and p53 are used to supplement histology. In this work, we aimed to assess CK20, CD44, Ki67 and p53 as immunohistochemical markers in patients with CIS through a systematic review and meta-analysis.

MATERIALS AND METHODS

A systematic review was performed by searching electronic databases for English-language studies published from January 2010 to April 2021. Studies were considered eligible if they evaluated the CK20, CD44, Ki67 and p53 expression in CIS.

RESULTS

In total, 15 references were suitable for quantitative review. The overall rate of CK20, CD44, Ki67 and p53 expression in CIS was 43%, 31%, 44%, 38%, respectively.

CONCLUSIONS

Our study supports the 2014 International Society of Urologic Pathology consensus that histological assessment remains the gold standard to diagnose urothelial CIS and suggests that a very close correlation between morphological, immunohistochemical and clinical data is essential to provide the best management for patients with bladder carcinoma.

p53 null phenotype is a "positive result" in urothelial carcinoma in situ

The concept of a "p53 null phenotype" (complete loss of staining) is well-recognized in the gynecologic pathology literature, implicitly reflecting that this staining pattern represents a TP53 mutation. However, in the genitourinary pathology literature, a p53 null phenotype has only been addressed regarding the prognosis of invasive urothelial carcinoma, and not as a diagnostic biomarker for urothelial carcinoma in situ (CIS). Herein, 25 cases of urothelial carcinoma in situ [diagnoses made on hematoxylin and eosin (H&E) stained sections] showing null pattern p53 staining were retrieved from 22 different patients (16 males and 6 females, age range 52-85 years; average 69.6 years), most commonly showing large cell pleomorphic pattern morphology. One representative tissue block per case was selected for next-generation DNA sequencing (NGS). All 21 cases (100%) passing quality control for NGS showed at least 1 TP53 mutation (majority nonsense or frameshift mutations), including 3 cases with 2 mutations and 3 cases with 3 mutations. Three patients with multiple available samples harbored 1 or more shared TP53 mutations at 2 different time points, indicating clonality of the temporally distinct lesions. Additionally, 2 patients had an additional unique TP53 mutation at a later time point, suggesting intratumoral heterogeneity and/or temporal clonal evolution. While urothelial CIS remains an H&E diagnosis in most cases, a p53 immunostain may be useful in a subset of challenging cases. This study demonstrates that a p53 null phenotype represents an aberrant result in urothelial CIS with supportive molecular analysis showing a previously unknown level of complexity for TP53 mutations among these noninvasive lesions. Adequate recognition of the p53 null phenotype as a "biologically supportive result", similar to strong and diffuse staining with p53, is important and may warrant a formal consensus statement for recommended p53 reporting (i.e., "wild type" versus "aberrant or mutant").

The clinicopathological and prognostic value of CD44 expression in bladder cancer: a study based on meta-analysis and TCGA data

CD44 is reported to be involved in tumor invasion and metastasis. However, the role of cancer stem cell marker CD44 in bladder cancer still remains controversial. Hence, the correlations between CD44 expression and the clinicopathological features and the prognosis of bladder cancer were investigated. Publications using immunohistochemical methods were identified. The Cancer Genome Atlas (TCGA) data were also analyzed. The odds ratios (ORs) or hazard ratios (HRs) with their 95% confidence intervals (95% CIs) were calculated. 14 studies involving 1107 tissue samples were included. CD44 expression in bladder cancer was lower than in non-tumor tissue samples (OR = 0.14, P = 0.005), which was consistent with TCGA data. CD44 expression was correlated with advanced T stage (OR = 1.76, P = 0.029) and lymph node metastasis (OR = 4.09, P < 0.001). Multivariate survival analysis showed that CD44 expression was not linked to tumor-specific survival, overall survival, and recurrence/relapse-free survival, but was associated with disease failure (HR = 2.912, 95% CI = 1.51-5.61). No relationships of CD44 expression with the clinicopathological features and overall survival were found from TCGA data. Our finding suggested that CD44 expression may be correlated with progression, metastasis, and disease failure of bladder cancer. However, further large-scale studies are needed.Abbreviations: CD44: Cluster of Differentiation 44; CIs: Confidence Intervals; CSCs: Cancer Stem Cells; EMT: Epithelial-mesenchymal Transition; HRs: Hazard Ratios; ORs: Odds Ratios; TCGA: The Cancer Genome Atlas.

Urothelial Carcinoma In Situ of the Bladder: Correlation of CK20 Expression With Adaptive Immune Resistance, Response to BCG Therapy, and Clinical Outcome

Immunohistochemical stains have been suggested to aid in diagnostically challenging cases of urothelial carcinoma in-situ (CIS). Although full thickness immunostaining for CK20 is supportive of CIS, a subset of CIS cases is CK20(-), the clinical significance of which was unknown. This study included 43 patients with primary diagnosis of bladder CIS including 32 with only CIS, 5 with CIS and separate noninvasive high-grade papillary urothelial carcinoma, and 6 with CIS and separate high-grade urothelial carcinoma with lamina propria invasion. Digital morphometric image analysis showed that the average nuclear areas of enlarged nuclei were similar in CK20(+) and CK20(-) CIS (26.9 vs. 24.5 µM2; P=0.31). Average Ki67 index for CK20(+) CIS was higher than CK20(-) CIS (31.1% vs. 18.3%; P=0.03). Patients with CK20(+) CIS [28 (65%)] and patients with CK20(-) CIS [15 (35%)] had the same rates of Bacillus Calmete-Guerin (BCG) failure but patients with CK20(-) CIS had higher stage progression [3 CK20(+) (11%) vs. 6 CK20(-) (40%); P=0.02]. Given recent approval of immune checkpoint inhibitors in patients with CIS refractory to BCG, programmed death ligand-1 expression and colocalization with CD8(+) lymphocytes was investigated as signature of adaptive immune response and was seen in 8 patients regardless of CK20 status and exclusively among patients who failed BCG. Our results confirm that negative CK20 IHC does not exclude CIS and that those patients have similar clinical outcomes as patients with CK20(+) CIS. Programmed death ligand-1 and CD8 colocalization seen among patients who failed BCG therapy is an easy assay to perform to identify patients who could potentially benefit from combined BCG therapy and immune checkpoint inhibition.

Urothelial carcinoma in situ: diagnostic update

Based on the current WHO 2016 classification, the spectrum of flat urothelial lesions with atypia includes reactive urothelial atypia, urothelial atypia of unknown significance, urothelial dysplasia, and urothelial carcinoma in situ (CIS). Classification along this continuous spectrum of atypia can be one of the most challenging areas in all genitourinary pathology. This review will focus on the diagnosis of urothelial CIS in routine clinical practice, emphasising histological criteria, histological spectrum (i.e., 'variant' types), adjunctive immunohistochemistry, intraoperative evaluation, and distinction from its morphological mimics.

Stage T1 bladder cancer: diagnostic criteria and pitfalls

Accurate pathological staging is crucial for patient management. Patients with T1 bladder cancer are at risk of recurrence, progression, and death of cancer. Recognition of early invasion (stage T1 disease) in urothelial carcinoma remains one of the most challenging areas in urological surgical pathology practice. A logical roadmap to T1 diagnosis would include careful evaluation of histological grade, stromal epithelial interface, characteristics of the invading epithelium, and the stroma associated responses. Tangential sectioning, crush and cautery artifacts, and associated inflammatory infiltrate are commonly encountered problems and the source of pitfalls. In this review, we outline diagnostic criteria, common pitfalls, and different histological patterns of invasion into the lamina propria. Current recommendations on reporting of biopsy and transurethral resection specimens, molecular biomarkers, clinical implications of T1 cancer diagnosis and recent developments on the T1 substaging are also discussed. Most T1 bladder cancer patients will benefit from conservative management after restaging transurethral resection of bladder and bacillus Calmette-Guérin maintenance. Patients with high risk features, such as concurrent urothelial carcinoma in situ, increased depth of invasion, lymphovascular invasion, and variant histology among others, should be considered for early cystectomy.

Diagnosis of urothelial carcinoma in situ using blue light cystoscopy and the utility of immunohistochemistry in blue light-positive lesions diagnosed as atypical

Carcinoma in situ (CIS) is difficult to visualize with white light cystoscopy (WLC), whereas blue light cystoscopy (BLC) using photosensitizing agents improves detection rates. We retrospectively reviewed transurethral biopsies of bladder tumors in which both WLC and BLC evaluations were performed (n = 135 samples from 79 patients). Biopsies were classified based on the presence/absence of fluorescence under BLC and the final pathological report (CIS/benign/atypical). Forty-one (30%) cases were diagnosed as CIS; of those, 38 (93%) were BLC(+), including 23 that were WLC(-). Conversely, 51 (38%) lesions were BLC(+) but classified as non-CIS. Eleven BLC(+) cases were diagnosed as "atypical." These cases were anonymized and reviewed by 7 pathologists for concordance and then immunostained for CK20, p53, and Ki-67. Immunohistochemistry results were interpreted as consistent with CIS if there was full-thickness staining of CK20, more than 50% p53-positive cells, and more than 50% Ki-67-positive cells. Review of BLC(+)/atypical cases showed a mean agreement of 79%, and none of the cases showed staining pattern consistent with CIS. Therefore, all 11 cases of BLC(+)/atypical were considered non-CIS for the final analysis. All patients with BLC(+)/atypical lesions had a history of intravesical Bacillus Calmette-Guerin and/or mitomycin. Using final pathology as the reference, sensitivity, specificity, and negative predictive value of BLC were 93% (confidence interval [CI], 80.1%-98.5%), 46% (CI, 35.4%-56.3%), and 94% (CI, 82.5%-97.8%), respectively. The low specificity of BLC leads to BLC(+) lesions with atypical diagnosis. Morphological classification of these lesions is fairly consistent among different pathologists. Immunohistochemistry for p53/CK20/Ki-67 in this setting is only helpful to potentially avoid overcalling CIS.

Precursor lesions of the urinary bladder

The classification of neoplastic precursor lesions in the urinary tract has evolved slowly with the gradual accumulation of clinicopathological data. Current nomenclature was codified most recently by the 2016 WHO classification, which is based on primary data with clinical outcome, consensus group statements and considerations of practical utility in routine diagnosis. This review discusses precursor lesions of urothelial, squamous and glandular lineage. For urothelial neoplasia, both flat lesions with atypia and early 'difficult-to-classify' proliferations are considered. Subtypes of squamous metaplasia, florid non-invasive squamous proliferations and frank squamous dysplasia are also addressed. Finally, rare glandular precursors of adenocarcinoma are reviewed, to include intestinal metaplasia, glandular dysplasia and villous adenoma. For each category, morphology (including differential diagnostic considerations), immunohistochemistry and any known molecular correlates are detailed. The goal is to provide a concise, practical up-to-date overview of this complex topic.

Contemporary Grading and Staging of Urothelial Neoplasms of the Urinary Bladder: New Concepts and Approaches to Challenging Scenarios

Grading and staging of urothelial neoplasm are the most crucial factors in risk stratification and management; both necessitate optimal accuracy and consistency. Several updates and recommendations have been provided though recent publications of the 4th edition of the World Health Organization classification, the 8th edition of the American Joint Committee on Cancer staging system, and the International Consultation on Urological Diseases-European Association of Urology updates on bladder cancer. Updates and recent studies have provided better insights into and approaches to the challenging scenarios in grading and staging of urothelial neoplasm; however, there remain aspects that need further investigation and refinement.

CK20 and p53 Immunohistochemical Staining Patterns in Urinary Bladder Specimens With Equivocal Atypia

Context.—

Urinary bladder flat carcinoma in situ (CIS) is a worrisome lesion, requiring aggressive surveillance and treatment. Cytokeratin 20 (CK20) and p53 are common immunohistochemical antibodies used to supplement CIS diagnosis in biopsy samples. However, existing data come primarily from unequivocally benign and malignant specimens.

Objective.—

To correlate these markers in specimens with borderline histology with outcomes.

Design.—

CK20 and p53 immunohistochemistry was analyzed for staining pattern, classified as CIS pattern (both stains yielding strong labeling of the area of concern), discordant (only 1 stain yielding CIS pattern), indeterminate (1 or both stains yielding partial or equivocal labeling), or benign (both stains yielding a benign pattern).

Results.—

Specimens with equivocal atypia (n = 69) from 65 patients were studied. There were 9 specimens (13%) that had a CIS staining pattern, 18 (26%) were discordant, 31 (45%) were indeterminate, and 11 (16%) were benign. Of the discordant specimens, 13 labeled for CK20 but not p53, whereas 5 showed the opposite. Most specimens (n = 47; 68%) were obtained from patients with a known history of bladder cancer, of which recurrence developed in 27, with an average interval of 37 months (range, 2–216 months). A subset (n = 22; 34%) had no prior history of bladder cancer, from which only 1 patient with CK20-positive/p53-equivocal staining later developed diagnostic carcinoma.

Conclusions.—

In our cohort of specimens with equivocal urothelial atypia, very few patients without a prior diagnosis of bladder cancer progressed to diagnostic cancer (1 of 22), suggesting that staining results should be interpreted with caution in de novo atypia. Patients with a known history of bladder cancer had a substantial rate of recurrence, independent of staining pattern.

Precursor Lesions of Urologic Malignancies

CONTEXT

- Precursor lesions of urologic malignancies are established histopathologic entities, which are important not only to recognize for clinical purposes, but also to further investigate at the molecular level in order to gain a better understanding of the pathogenesis of these malignancies.

OBJECTIVE

- To provide a brief overview of precursor lesions to the most common malignancies that develop within the genitourinary tract with a focus on their clinical implications, histologic features, and molecular characteristics.

DATA SOURCES

- Literature review from PubMed, urologic pathology textbooks, and the 4th edition of the World Health Organization Classification of Tumours of the Urinary System and Male Genital Organs. All photomicrographs were taken from cases seen at Weill Cornell Medicine or from the authors' personal slide collections.

CONCLUSIONS

- The clinical importance and histologic criteria are well established for the known precursor lesions of the most common malignancies throughout the genitourinary tract, but further investigation is warranted at the molecular level to better understand the pathogenesis of these lesions. Such investigation may lead to better risk stratification of patients and potentially novel treatments.

Flat pattern of nephrogenic adenoma: previously unrecognized pattern unveiled using PAX2 and PAX8 immunohistochemistry

Nephrogenic adenoma is a benign lesion of the urinary tract, particularly the urinary bladder. It is a gross and microscopic mimicker of urothelial neoplasm or metastatic carcinoma. Several histological patterns (tubular, tubulocystic, polypoid, papillary, fibromyxoid) have been recognized, but a flat pattern has not been described. Histologically, nephrogenic adenoma consists of tubules, cysts or papillae lined by flat to polygonal cells with frequent hobnail appearance. The stroma is often edematous or has a granulation tissue-like appearance with acute or chronic inflammation. By immunohistochemistry, nephrogenic adenomas are positive for renal epithelial markers CK7, CD10 and alpha-methylacyl-coenzyme A racemase, and negative for bladder urothelium or prostate markers. Recent studies have shown that nephrogenic adenomas are positive for PAX2 and PAX8. We encountered an interesting case of tubular nephrogenic adenoma with adjacent areas suspicious of flat urothelial atypia. Immunohistochemistry for PAX2 and PAX8 were positive in these areas, unveiling a flat pattern of nephrogenic adenoma. This case prompted us to study 15 cases of nephrogenic adenoma to determine additional instances of flat pattern and to assess the value of PAX2 and PAX8 immunoreactivity to diagnose nephrogenic adenoma. PAX2 and PAX8 immunostaining was positive in 14/15 and 15/15 cases, respectively. The flat pattern was present at least focally adjacent to tubular, polypoid and papillary areas, in 8/15 cases of nephrogenic adenoma. In conclusion, the flat pattern is a common finding in nephrogenic adenomas, but easily under recognized by morphologic examination and may be confused with flat urothelial lesions with atypia. Immunostains for PAX2 and PAX8 are useful in the detection of nephrogenic adenomas and particularly unveil those nephrogenic adenomas with flat pattern.