The role of immunohistochemistry in the diagnosis of urinary bladder neoplasms

The Application and Pitfalls of Immunohistochemical Markers in Challenging Diagnosis of Genitourinary Pathology

CONTEXT.—

The morphologic features of different entities in genitourinary pathology overlap, presenting a diagnostic challenge, especially when diagnostic materials are limited. Immunohistochemical markers are valuable when morphologic features alone are insufficient for definitive diagnosis. The World Health Organization classification of urinary and male genital tumors has been updated for 2022. An updated review of immunohistochemical markers for newly classified genitourinary neoplasms and their differential diagnosis is needed.

OBJECTIVE.—

To review immunohistochemical markers used in the diagnosis of genitourinary lesions in the kidney, bladder, prostate, and testis. We particularly emphasized difficult differential diagnosis and pitfalls in immunohistochemistry application and interpretation. New markers and new entities in the 2022 World Health Organization classifications of genitourinary tumors are reviewed. Recommended staining panels for commonly encountered difficult differential diagnoses and potential pitfalls are discussed.

DATA SOURCES.—

Review of current literature and our own experience.

CONCLUSIONS.—

Immunohistochemistry is a valuable tool in the diagnosis of problematic lesions of the genitourinary tract. However, the immunostains must be carefully interpreted in the context of morphologic findings with a thorough knowledge of pitfalls and limitations.

Primary high-grade urothelial carcinoma of prostate with prostatic hyperplasia: a rare case report and review of the literature

BACKGROUND

Primary urothelial carcinoma in the prostate (UCP) is extremely rare and occurs most frequently in the bladder. There are only dozens of primary cases reported in the literature. Here, we describe a rare case of primary UCP and review the literature.

CASE PRESENTATION

A 67-year-old widowed male, was referred to our hospital due to the frequency, and urgency of dysuria. Magnetic resonance imaging (MRI) examination revealed prostate size was about 57 mm × 50 mm × 54 mm, increased prostatic transitional zone, and surrounding of prostatic duct indicate bar isointense T1, short T2, hyperintense DWI, and hyposignal ADC (PI-RADS 3); posterior of peripheral zone indicate patchy isointense T1, short T2, hyperintense DWI, and hyposignal ADC (PI-RADS 5). Subsequently, the patient underwent a transrectal prostate biopsy. Histopathological and immunohistochemical (IHC) assessments showed prostatic high-grade urothelial carcinoma with benign prostatic hyperplasia. Finally, the patient underwent laparoscopic radical prostatectomy. Four months after surgery, CT plain and enhanced scan revealed thickening of the bladder wall. On further workup, cystoscopy revealed lymphoid follicular changes in the cut edge of the radical prostatectomy, and cystoscopic biopsies showed the malignant tumor.

CONCLUSIONS

Prostatic urothelial carcinoma should always be considered if the patient with severe lower urinary tract symptoms or hematuria, PSA, and digital rectal examination without abnormalities, without a personal history of urothelial cancer, but contrast-enhanced MRI showed the lesion located in the prostate. As of right now, radical surgical resections remain the most effective treatment. The effectiveness of neoadjuvant or adjuvant chemotherapy is still controversial.

Comparison of Immunohistochemistry Expression of CK7, HMWK and PSA in High-Grade Prostatic Adenocarcinoma and Bladder Transitional Cell Carcinoma

Background & Objective:

Prostate adenocarcinoma is the most common malignancy in males, and the urothelial bladder carcinoma is also prevalent. The histological characteristic of these two tumors is very similar in high-grade cases, and their differentiation is difficult. This study was performed to compare the immunohistochemistry panel of high-grade prostate adenocarcinomas and high-grade urothelial bladder carcinomas.

Methods:

In this cross-sectional study, 36 cases of prostate adenocarcinoma and 36 urothelial bladder carcinoma samples were collected from the pathology department of Shahid Beheshti Hospital in Hamedan. For each sample, expression of Cytokeratin 7, high-molecular-weight cytokeratin and Prostate-specific antigen markers was evaluated by immunohistochemistry. Comparison of expression of these markers in high-grade bladder tumors and prostate tumors was made by SPSS 25 using Chi-square test.

Results:

In this study, the Cytokeratin 7 positivity was seen in 88.9% of bladder cancer versus 27.8% of prostate cancer samples. High-molecular-weight cytokeratin positive immunoreactivity was noted in 55.6% of bladder cancer and 5.6% of prostate cancer samples. Prostate-specific antigen marker showed positive results in 94.4% of prostate cancer samples, but no positivity was evident in those of bladder cancer.

Conclusion:

A panel of immunohistochemical stains can be used to differentiate high-grade prostate adenocarcinoma from urothelial bladder carcinoma in those cases which are challenging to diagnose.

Diagnostic and prognostic roles of CK20 in the pathology of urothelial lesions. A systematic review

Cytokeratin 20 (CK20) is one of the most common immunohistochemical markers in the routine practice of a pathology lab, as biopsies from the urinary tract encompass a wide spectrum of lesions which may pose issues in their detection and classification. In this review, we aim to outline the diagnostic accuracy and prognostic value of CK20 in flat urothelial lesions, papillary non-invasive and invasive urothelial carcinoma, molecular subgroups and variant histology, and we briefly discuss its limitations and potential pitfalls.

Non-urothelial carcinomas of the bladder

Non-urothelial carcinomas involving the bladder are uncommon and often diagnostically challenging. These carcinomas may show squamous, adenocarcinomatous or neuroendocrine features, with immunohistochemical stains aiding the diagnosis in only a subset of cases. The clinical history in non-urothelial bladder carcinomas is important, given that the differential diagnosis often includes secondary involvement of the bladder by direct extension or metastasis from carcinomas at other sites. This paper will review non-urothelial carcinomas in each of these three morphological categories, emphasising recent changes in diagnostic grouping and challenges in the histopathological diagnosis. Review of bladder cancers with squamous morphology will include discussion of conventional squamous cell carcinoma and verrucous carcinoma and their distinction from urothelial carcinoma with extensive squamous differentiation. Bladder carcinomas with adenocarcinomatous change will include primary bladder adenocarcinoma, urachal adenocarcinoma and tumours of Müllerian type. Finally, neuroendocrine neoplasms of the bladder, including well-differentiated neuroendocrine tumour and neuroendocrine carcinomas, will be discussed. Associated surface findings, risk factors and prognostic features will be described.

Morphological and Immunohistochemical Biomarkers in Distinguishing Prostate Carcinoma and Urothelial Carcinoma: A Comprehensive Review

The differential diagnosis between high-grade prostate carcinoma and infiltrating urothelial carcinoma (UC) in transurethral resection prostate specimens as well as cystoprostatectomy specimens may often be challenging due to morphologic and clinical overlap of the 2 entities. Such distinction has critical therapeutic and staging consequences, yet it is hampered by both issues in morphology and by the low accuracy rates of single immunohistochemical markers, as reported in literature. This review aims to provide a comprehensive analysis of the available morphological and immunohistochemical parameters, which may allow to discriminate between prostate carcinoma and urothelial carcinoma in the proper clinical context and to discuss their diagnostic applications in daily practice.

Evolving concepts and use of immunohistochemical biomarkers in flat non-neoplastic urothelial lesions: WHO 2016 classification update with diagnostic algorithm

CONTEXT

The classification of flat non-neoplastic urothelial lesions has been evolved through the years in the attempt to better define a spectrum of morphologic entities with somewhat overlapping features. Differentiating these lesions is important because of differences in patient management and clinical outcome. Materials and methods and objective: A systematic review of the literature has been carried out in order to (1) assess the most striking clinical features of each lesion and (2) identify those morphological traits and immunophenotypical markers which may aid in the differential diagnosis.

RESULTS AND CONCLUSION

Our results point out the importance of a proper definition of flat non-neoplastic urothelial lesions in order to predict clinical behaviour and allow tailored patient management; therefore, we attempted to construct a novel and "easy to use" algorithm for a clear, standardized and evidence-based pathological diagnosis.

Practical Applications of Immunohistochemistry in the Diagnosis of Genitourinary Tumors

Context.—

Pathologic diagnosis of tumors in the genitourinary system can be challenging based on morphology alone, particularly when diagnostic material is limited, such as in core biopsies. Immunohistochemical stain can be a useful tool to aid in the diagnosis.

Objective.—

To provide an update on practical applications and interpretation of immunohistochemical stains in the diagnosis of tumors in prostate, kidney, bladder, and testis. We particularly focus on difficult differential diagnoses, providing our insights in frequently encountered challenging situations. Commonly used immunohistochemical panels are discussed.

Data Sources.—

Review of literature and our own experience.

Conclusion.—

Immunohistochemical stain is a valuable tool in the diagnosis of genitourinary tumors when appropriately used.

The Utility of GATA3 in the Diagnosis of Urothelial Carcinomas With Variant Morphologic Patterns

The transcription factor GATA3 is a recently described biomarker that is highly expressed in bladder and breast carcinomas. Although it has shown sensitivity as a marker of primary bladder carcinomas with purely urothelial differentiation, the ability of GATA3 to label primary bladder carcinomas with variant morphologic patterns has been incompletely assessed to date. The current study was designed to determine whether GATA3 staining is retained in "unconventional" bladder carcinomas. Eighty-eight cases of primary bladder cancers were retrieved from the authors' institutional archive, and they included the following histomorphologic types: 6 small cell carcinomas, 12 sarcomatoid carcinomas, 17 adenocarcinomas (both primary and urothelial variants with glandular differentiation), 24 micropapillary carcinomas, and 27 squamous cell carcinomas (both primary and urothelial variants with squamous differentiation). A tissue microarray was constructed and automated immunostaining for GATA3 (Clone L50-823, Biocare Medical, Concord, CA) was performed using standard technique. Among the 5 variants of unconventional bladder carcinoma, only the micropapillary and sarcomatoid forms exhibited consistent and strong immunolabeling for GATA3. Hence, the sensitivity of this determinant is diminished in several histologic forms of primary bladder carcinoma. That fact will affect the interpretation of GATA3 stains in the context of possible metastasis from primary bladder carcinomas with variant morphologic patterns, as well as their distinction from secondary bladder involvement by tumors of nonurothelial origin.

S100P as a Marker for Urothelial Histogenesis: A Critical Review and Comparison With Novel and Traditional Urothelial Immunohistochemical Markers

S100P, or placental S100, is a member of a large family of S100 proteins and considered to be a promising immunohistochemical marker to support urothelial differentiation. This review synthesizes published data regarding the expression of S100P in urothelial carcinoma across histological grade and variant patterns, and in other malignancies, in an effort to summarize the state of understanding of this marker and evaluate its potential. We provide also a broad comparison of S100P with other contemporary and traditional urothelial markers and outline the potential utility of S100P in various diagnostically challenging scenarios. Taken in context, we recommend that to provide immunohistochemical support for consideration of urothelial differentiation, S100P may be included in a panel of markers (due to its high sensitivity), with better established (GATA3) and more specific (uroplakin 2) markers, for comparison with corresponding markers of other primary sites under consideration, depending on the clinical context. We emphasize that the overall most appropriate panel for any given case depends on the differential diagnosis engendered by the morphology encountered, and the constellation of clinical findings. As always with immunohistochemical panels, expected positive and negative markers for each diagnostic consideration should be included. Finally, since as of date there are no optimally sensitive or specific markers of urothelial differentiation, all final diagnoses relying on immunohistochemical support should be made in the appropriate clinical and histological context.

The Application of Immunohistochemical Biomarkers in Urologic Surgical Pathology

Context

Tumors of the genitourinary tract can be diagnostically challenging, particularly in core biopsies and cystoscopic biopsies with limited material. Immunohistochemistry is a valuable tool to use when morphology alone is insufficient for diagnosis.

Objectives

To review tumors and benign lesions of the kidney, urinary bladder, prostate gland, testis, and paratesticular structures with an emphasis on difficult differential diagnoses, as well as staining patterns in normal tissue. Recommended immunohistochemical stain panels are discussed that can assist in the diagnostic workup.

Data Sources

Review of current literature.

Conclusions

Immunohistochemistry is a valuable tool, assisting in the diagnosis of problematic tumors and benign lesions of the genitourinary tract.

Best practices recommendations in the application of immunohistochemistry in the bladder lesions: report from the International Society of Urologic Pathology consensus conference

The bladder working group of the 2013 International Society of Urologic Pathology (ISUP) Conference on Best Practices Recommendation in the Application of Immunohistochemistry (IHC) in Urologic Pathology discussed 5 settings in which IHC is commonly used in clinical practice. With regard to markers for urothelial differentiation, the committee found that there is no ideal marker or established panel to confirm urothelial differentiation. On the basis of the differential diagnostic consideration, positivity for GATA3, CK20, p63, and either high-molecular weight cytokeratin (HMWCK) or cytokeratin (CK)5/6 is of value in proving urothelial differentiation in the appropriate morphologic and clinical context. With regard to the role of IHC in the distinction of reactive atypia from urothelial carcinoma in situ, the committee recommended that morphology remains the gold standard in this differential diagnosis and that, at best, the IHC panel of CK20/p53/CD44(s) has potential utility but is variably used and has limitations. The immunostaining pattern must be interpreted with strict morphologic correlation, because overreliance on IHC may be misleading, particularly in the posttreatment setting. IHC has no role in the distinction of dysplasia versus carcinoma in situ and in the grading of papillary urothelial carcinoma. IHC may have a limited but distinct role in staging of bladder cancer. In a subset of cases, depending on the clinical and histologic context, broad-spectrum cytokeratins (to identify early or obscured invasion) and desmin (distinction of muscle from desmoplasia and to highlight muscle contours for subclassification) may be helpful. Limited experience and conflicting data preclude smoothelin or vimentin to be recommended routinely for subclassifying muscle type at this time. In the workup of a spindled cell proliferation of the bladder and in limited specimens, we recommend an immunohistochemical panel of 6 markers including ALK1, SMA, desmin, cytokeratin (AE1/AE3), and p63 with either of HMWCK or CK5/6. Currently, there are no prognostic immunohistochemical or molecular studies that are recommended to be routinely performed on biopsy or resection specimens.

Sarcomatoid variant of urothelial carcinoma (carcinosarcoma, spindle cell carcinoma): a review of the literature

Background. Sarcomatoid variant of urothelial carcinoma (SVUC) was added to the WHO classification in 2004. Aims. To review the literature. Materials and Method. Various internet databases were used. Result. SVUCs are rare biphasic malignant neoplasms exhibiting morphologic/immunohistochemical evidence of epithelial and mesenchymal differentiation with the presence or absence of heterologous elements. Some cases of SVUC have been associated with radiation therapy and cyclophosphamide treatment. Patients' ages range from 50 to 77 years (mean age 66). Patients tend to be younger and they more commonly presented with high-grade histology and advanced stage disease, in comparison with patients who had conventional urothelial carcinoma (CUC). Results of molecular/genetic studies strongly argue for a common monoclonal cell origin of both the epithelial and mesenchymal components in SUVC. The cancer specific survival of SVUC is poor in comparison with CUC. Radical surgical excision and chemoradiation may be associated with improved prognosis; chemoradiation as an organ preserving alternative to radical excision may be associated with improved outcome. There is no consensus opinion on the best treatment modalities for SUVC. Conclusions. SVUC is rare and is associated with inferior outcome compared with CUC. A multicentre trial of various treatment options is required. Cases of SVUC should be reported.

Signet-ring-cell carcinoma of stomach metastatic to the bladder: a case report with cytological and histological correlation and literature review

BACKGROUND

Bladder involvement by a secondary tumor is fairly rare and an uncommon source of bladder metastasis is the stomach.

CASE REPORT

The authors report a case of a 38-year-old man with a bladder metastasis from a gastric signet-ring-cell (SRC) adenocarcinoma who presented with ematuria. The clinical history and the presence of SRCs in the voided urinary cytology and histologically in the suburothelial connective, with an overlying intact urothelium suggested a diagnosis of bladder metastasis from gastric carcinoma.

CONCLUSION

Bladder involvement by a secondary tumor is very rare, and a SRC carcinoma metastatic to the bladder, albeit extremely rare, should be considered in the differential diagnosis.

Comparison of different adjuvant radiotherapy approaches in childhood bladder/prostate rhabdomyosarcoma treated with conservative surgery

BACKGROUND AND PURPOSE

Multimodality treatment approaches provide high local control and satisfying overall survival (OS) for children with localized bladder and/or prostate rhabdomyosarcoma (BP-RMS). However, current strategies including surgery and conventional radiotherapy are compromised by high rates of long-term genitourinary adverse effects. Therefore, a planning study combining organ preserving surgery with three different innovative adjuvant radiotherapy approaches was performed.

PATIENTS AND METHODS

A case of a 21-month-old boy with BP-RMS treated with polychemotherapy according to the CWS 2002-P protocol, prostatectomy, partial cystectomy, and adjuvant high dose rate brachytherapy (HDR-BT) was used to perform a planning study comparing HDR-BT with intensity-modulated radiotherapy (IMRT) and intensity-modulated proton therapy (IMPT) planning.

RESULTS

All modalities provide good coverage of the target volume and spare critical normal tissues. Rectum doses could be reduced by 2/3 using IMPT and by 1/3 using BT compared to IMRT. In terms of sparing the pelvis growth plates, BT and IMPT are also superior to IMRT.

CONCLUSION

All modalities provide good sparing of normal tissue. BT and IMPT are superior to IMRT with regard to doses on rectum and growth plates. BT is equivalent to IMPT in adequately selected tumors.

Unique patterns of metastases in common and rare types of malignancy

This review on the unique patterns of metastases by common and rare types of cancer addresses regional lymphatic metastases but also demonstrates general principles by consideration of vital organ metastases. These general features of successfully treated metastases are relationships to basic biological behavior as illustrated by disease-free interval, organ-specific behavior, oligo-metastatic presentation, genetic control of the metastatic pattern, careful selection of patients for surgical resection, and the necessity of complete resection of the few patients eligible for long-term survival after resection of vital organ metastasis. Lymph node metastases, while illustrating these general features, are not related to overall survival because lymph node metastases themselves do not destroy a vital organ function, and therefore have no causal relationship to overall survival. When a cancer cell spreads to a regional lymph node, does it also simultaneously spread to the systemic site or sites? Alternatively, does the cancer spread to the regional lymph node first and then it subsequently spreads to the distant site(s) after an incubation period of growth in the lymph node? Of course, if the cancer is in its incubation stage in the lymph node, then removal of the lymph node in the majority of cases with cancer cells may be curative. The data from the sentinel lymph node era, particularly in melanoma and breast cancer, is consistent with the spectrum theory of cancer progression to the sentinel lymph node in the majority of cases prior to distant metastasis. Perhaps, different subsets of cancer may be better defined with relevant biomarkers so that mechanisms of metastasis can be more accurately defined on a molecular and genomic level.

E-cadherin expression in plasmacytoid, signet ring cell and micropapillary variants of urothelial carcinoma: comparison with usual-type high-grade urothelial carcinoma

Loss of E-cadherin expression has been linked to the invasive phenotypes of a variety of neoplasms, including lobular breast cancer. The expression of E-cadherin in variants of urothelial carcinoma relative to usual-type urothelial carcinoma, maximum depth of invasion and angiolymphatic invasion has not been well characterized. A total of eight cases of micropapillary urothelial carcinoma, four cases of plasmacytoid urothelial carcinoma, two cases of urothelial carcinoma with signet ring cell differentiation and two cases of urothelial carcinoma with mixed plasmacytoid and signet ring cell differentiation, all obtained from cystectomy/cystoprostatectomy cases, were identified. In all nine cases of usual-type invasive and noninvasive high-grade urothelial carcinoma were also included in the study. Immunohistochemical staining of E-cadherin was performed in all cases. Pathological parameters including depth of invasion and presence of angiolymphatic invasion were documented. Maximum depth of invasion: In micropapillary urothelial carcinoma, extravesical extension was seen in three of eight cases; muscularis propria invasion in four of eight cases; and lamina propria invasion in one of eight cases. In plasmacytoid urothelial carcinoma, extravesical extension was observed in two of four cases, and muscularis propria invasion and lamina propria invasion in one of four cases each. In urothelial carcinoma with signet ring cell differentiation, extravesical extension and muscularis propria invasion was seen in one of two cases each. In urothelial carcinoma with mixed plasmacytoid and signet ring cell differentiation, muscularis propria invasion and lamina propria invasion was observed in one of two cases each. In usual-type high-grade urothelial carcinoma, extravesical extension was seen in six of nine cases and noninvasive in three of nine cases. In angiolymphatic invasion, micropapillary urothelial carcinoma was observed in eight of eight cases; plasmacytoid urothelial carcinoma in two of four cases; urothelial carcinoma with signet ring cell differentiation in one of two cases; and urothelial carcinoma with mixed plasmacytoid and signet ring cell differentiation in one of two cases. Usual-type high-grade urothelial carcinoma was seen in six of nine cases. E-cadherin expression: All eight cases of micropapillary urothelial carcinoma were positive for E-cadherin in the micropapillary component and adjacent usual-type urothelial carcinoma. The four cases of plasmacytoid urothelial carcinoma, two cases of urothelial carcinoma with signet ring cell differentiation and two cases of urothelial carcinoma with mixed plasmacytoid and signet ring cell differentiation were all negative for E-cadherin. All nine additional cases of usual-type high-grade urothelial carcinoma were diffusely positive for E-cadherin. E-cadherin is diffusely positive in usual-type urothelial carcinoma and micropapillary urothelial carcinoma, irrespective of pathological stage and angiolymphatic invasion. Loss of E-cadherin expression may be a marker of plasmacytoid and signet ring cell differentiation in urothelial carcinoma.

Validation and reproducibility of a microarray-based gene expression test for tumor identification in formalin-fixed, paraffin-embedded specimens

Tumors whose primary site is challenging to diagnose represent a considerable proportion of new cancer cases. We present validation study results for a gene expression-based diagnostic test (the Pathwork Tissue of Origin Test) that aids in determining the tissue of origin using formalin-fixed, paraffin-embedded (FFPE) specimens. Microarray data files were generated for 462 metastatic, poorly differentiated, or undifferentiated FFPE tumor specimens, all of which had a reference diagnosis. The reference diagnoses were masked, and the microarray data files were analyzed using a 2000-gene classification model. The algorithm quantifies the similarity between RNA expression patterns of the study specimens and the 15 tissues on the test panel. Among the 462 specimens, overall agreement with the reference diagnosis was 89% (95% CI, 85% to 91%). In addition to the positive test results (ie, rule-ins), an average of 12 tissues for each specimen could be ruled out with >99% probability. The large size of this study increases confidence in the test results. A multisite reproducibility study showed 89.3% concordance between laboratories. The Tissue of Origin Test makes the benefits of microarray-based gene expression tests for tumor diagnosis available for use with the most common type of histology specimen (ie, FFPE).

Structural and functional analysis of human prostatic acid phosphatase

Prostatic acid phosphatase (PAP) is the most abundant phosphatase in human prostate tissue/secretions. It is a clinically important protein for its relevance as a biomarker of prostate carcinoma. Furthermore, it has a potential role in fertilization. We describe here most of the features of PAP including gene regulation, gene/protein structure, functions, its role in tumor progression and evolutionary features. PAP has phosphatase activity and is an extensively studied biomarker of prostate cancer. The major action of PAP is to dephosphorylate macromolecules with the help of catalytic residues (His(12) and Asp(258)) that are located in the cleft between two domains. This article will be of great interest to all those scientists who are working in the area of prostate pathophysiology.

Pseudoneoplastic mimics of prostate and bladder carcinomas

CONTEXT

The differential diagnoses of prostatic carcinoma and bladder epithelial neoplasms include several histologic mimics that should be known to avoid misdiagnosis.

OBJECTIVE

To discuss pseudoneoplastic lesions of the prostate and bladder that could potentially be confused with prostatic carcinoma and bladder epithelial neoplasms, respectively, with specific focus on their distinguishing histopathologic features.

DATA SOURCES

Relevant published literature and authors' experience.

CONCLUSIONS

Pseudoneoplastic lesions in the prostate include those of prostatic epithelial origin, the most common being atrophy, adenosis (atypical adenomatous hyperplasia), basal cell hyperplasia, and crowded benign glands, as well as those of nonprostatic origin, such as seminal vesicle epithelium. Such lesions often mimic lower-grade prostatic adenocarcinoma, whereas others, such as clear cell cribriform hyperplasia and granulomatous prostatitis, for example, are in the differential diagnosis of Gleason adenocarcinoma, Gleason grade 4 or 5. Pseudoneoplastic lesions of the urinary bladder include lesions that could potentially be confused with urothelial carcinoma in situ, such as reactive urothelial atypia, and others, such as polypoid/papillary cystitis, where papillary urothelial neoplasms are the main differential diagnostic concern. Several lesions can mimic invasive urothelial carcinoma, including pseudocarcinomatous hyperplasia, von Brunn nests, and nephrogenic adenoma. Diagnostic awareness of the salient histomorphologic and relevant immunohistochemical features of these prostatic and urinary bladder pseudoneoplasms is critical to avoid rendering false-positive diagnoses of malignancy.

Urothelial carcinoma of the bladder, lipid cell variant: clinicopathologic findings and LOH analysis

In this report, we present the clinicopathologic features of 27 cases of the lipid cell variant of urothelial bladder carcinoma. This is a rare variant of bladder cancer recognized by the current WHO classification of urologic tumors. The lipid cell component varied from 10% to 50% of the tumor specimen; in 11 cases the lipid cell component composed greater than 30% of the tumor. The architectural pattern of the tumor varied from solid expansile to infiltrative nests. The large epithelial tumor cells had an eccentrically placed nucleus and abundant vacuolated cytoplasm resembling signetring lipoblasts. Mucin stains were negative in all the cases. Typical features of high grade conventional urothelial carcinoma were present in all the cases with micropapillary or plasmacytoid carcinoma in 2 and 1 cases, respectively; extensive squamous or glandular differentiation was present in 2 additional cases. Most neoplastic cells had nuclei of intermediate nuclear grade with occasional nuclear pleomorphism. Immunohistochemical staining showed that the lipid cell component was positive for cytokeratins 7, 20, CAM 5.2, high molecular weight (34ssE12) and AE1/AE3, epithelial membrane antigen, and thrombomodulin; vimentin and S100 protein were negative. The loss of heterozygosity (LOH) analysis was done on 8 cases using 4 polymorphic microsatellite markers (D9S171, D9S177, IFNA, and TP 53); LOH at least in 1 marker was present in 6 cases. The LOH results were the same for lipid variant and conventional urothelial carcinoma. Pathologic stage was Ta (n=1), T1 (=2), T2, at least (n=7), T3a (n=4), T3b (n=8), and T4a (n=5). Electron microcopy analysis based on 2 cases supported lipid content in tumor cells. Follow-up information was available in all the cases, ranging from 6 to 58 months (mean, 28 mo). Sixteen of the patients died of disease at 16 to 58 months (mean, 33 mo) and 8 patients were alive with disease at 8 to 25 months (mean, 22 mo). Another 3 patients died of other causes at 6 to 15 months (mean, 10 mo). In summary, lipid cell urothelial bladder carcinoma is typically associated with advanced stage high-grade urothelial carcinoma, in which the prognosis is poor and clonally related to the concurrent conventional urothelial carcinoma. In limited samples, it may be misdiagnosed as liposarcoma, sarcomatoid carcinoma (carcinosarcoma), or signetring cell carcinoma. Morphologic distinction from other malignant neoplasms with lipid cell phenotype is critical for its clinical management.

[Plasmacytoid urothelial carcinoma of the bladder: a case report]

We experienced a case of plasmacytoid urothelial carcinoma of the bladder. A 79-year-old man was referred with urinary frequency. Computed Tomography, Magnetic Resonance Imaging and ultra-sonography of the abdomen showed a diffuse and invasive mass occupying most of the bladder. Cystoscopy showed mostly non papillary tumor in the bladder, which was resected. Pathological examination of the specimen showed a diffuse monotonous cellular infiltration that invaded the lamina propria and the muscularis propria. He received radical cystectomy, and two cycles of systemic chemotherapy were performed with methotrexate, etoposide, vinblastine, and cisplatin, due to a lymphnode metastasis (pT3a, pN1, M0). He was disease free for 11 months. The tumor cells were medium-sized, round with eosinophilic cytoplasm and eccentric nuclei, producing a plasmacytoid appearance. Immunohistochemical studies were positive for epithelial markers and negative for lymphoid markers. So, we could diagnose as plasmacytoid urothelial carcinoma. This is a rare tumor. This case is the 30th case in the English literature.

The current classification of urothelial neoplasms

The classification of urothelial neoplasms has been a subject of significant controversy and debate over the last decade. Only recently has a general level of agreement developed on the utility of the classification first proposed by the World Health Organization and the International Society of Urologic Pathology in 1998. Recent adoption of this scheme in therapeutic guidelines indicates the clinical utility of the system. In this review a brief historical perspective is presented, followed by a review of the classification system, the histological criteria for the specific categories and the clinical significance of these diagnoses.

Histological variants of urothelial carcinoma: diagnostic, therapeutic and prognostic implications

It is well established that invasive urothelial carcinoma, involving the urinary bladder and renal pelvis, has marked propensity for divergent differentiation. In recent years, several 'variant' morphologies have been described and most have been recognized in the 2004 World Health Organization Classification. These histological variants of urothelial carcinoma have clinical significance at various levels, including diagnostic, that is, awareness of the morphological variant is essential in order to avoid diagnostic misinterpretations; prognostic for patient risk stratification; and therapeutic, where a diagnostic assignment of a particular variant may be associated with the administration of a therapy distinctive from that used in conventional invasive urothelial carcinoma. The diagnoses of micropapillary urothelial carcinoma, small-cell carcinoma, lymphoepithelioma-like carcinoma and sarcomatoid carcinoma are prime examples where treatment protocols may be different than the usual muscle-invasive bladder cancer. This review discusses the variants of urothelial carcinoma, outlining for each the diagnostic features, differential diagnostic considerations and the clinical significance.

Urachal carcinoma: a clinicopathologic analysis of 24 cases with outcome correlation

BACKGROUND

Urachal carcinomas occur mostly in the bladder dome, comprising 22% to 35% of vesical adenocarcinomas, and are generally treated by partial cystectomy with en bloc resection of the median umbilical ligament and umbilicus. Detailed pathologic studies with clinical outcome correlation are few.

DESIGN

We reviewed histologic material and clinical data from 24 cases selected from a database of 67 dome-based tumors diagnosed and treated at our institution from 1984 to 2005. Follow-up information was available for all 24 patients.

RESULT

The mean age at diagnosis was 52 years (range: 26 to 68 y). Fifteen patients were male and 9 were female. Location was the dome in 23 and dome and anterior wall in 1. Thirteen cases were pure adenocarcinoma, not otherwise specified, 9 were enteric type adenocarcinoma, and 2 were adenocarcinoma with focal components of lymphoepithelioma-like carcinoma and urothelial carcinoma with cytoplasmic clearing. Signet ring cell features were focally seen in 2 cases. Cystitis cystica and cystitis glandularis were seen in 4 and 2 cases, respectively. In all instances but 1, cystitis cystica/glandularis was focal and predominantly in the bladder overlying the urachal neoplasm. Urachal remnants were identified in 15 cases: the urachal epithelium was benign urothelial-type in 6 cases and showed adenomatous changes in 9. The overlying bladder urothelium was colonized by adenocarcinoma in 3 cases. In all 3, urachal remnants were identified and showed transition from benign to adenomatous epithelium. On immunohistochemistry, these tumors were positive for CK20 and variably positive for CK7 and 34BE12. The majority showed a cytoplasmic membranous staining pattern for beta-catenin, although in 1 case, focal nuclear immunoreactivity was identified. The Sheldon pathologic stage was pT1 in 0, pT2 in 2, pT3a in 8, pT3b in 11, pT3c in 1, pT4a in 1, and pT4b in 1 patient. One patient had a positive soft tissue margin. The mean follow-up period was 40 months (range: 0.3 to 157.6 mo). Seven of 24 (29%) cases recurred locally. The incidence of local recurrence was higher in patients who underwent a partial cystectomy alone (37.5%) versus those who had a more radical surgery (27%). Distant metastases occurred in 9 (37.5%) patients, 4 of whom had no prior local recurrence. Seven patients (29%) died of the disease. All cases with locally recurrent and metastatic disease belonged to stage pT3 or higher.

CONCLUSIONS

Pathologic stage is an important prognostic factor in urachal carcinoma. Surface urothelial involvement by carcinoma and presence of cystitis cystica/glandularis do not necessarily exclude the diagnosis of urachal carcinoma. Immunostains do not unequivocally discriminate a urachal from a colorectal carcinoma, but diffuse positivity for 34BE12 would support, and diffuse nuclear immunoreactivity for beta-catenin would militate against, a diagnosis of urachal carcinoma. Local recurrence may be owing to seeding within the distal urothelial tract, particularly in tumors with a configuration that is polypoid and which open into the bladder cavity. The type of surgery performed may have an effect on local recurrence despite negative margins of resection.

Differential expression of immunohistochemical markers in bladder smooth muscle and myofibroblasts, and the potential utility of desmin, smoothelin, and vimentin in staging of bladder carcinoma

Distinguishing bladder muscularis propria from muscularis mucosae can be problematic especially in transurethral resection specimens performed for bladder carcinoma. Moreover, bladder carcinoma can be associated with a proliferative/desmoplastic myofibroblastic response that can resemble smooth muscle and potentially lead to overdiagnosis of muscularis propria invasion. The aim of this study was to investigate the potential role of immunohistochemistry in staging bladder carcinoma by evaluating the expression of different markers in myofibroblasts and nonvascular smooth muscle cells in 15 cases of invasive bladder carcinoma. Reactive myofibroblasts were consistently positive for vimentin and smooth muscle actin, consistently negative for caldesmon, desmin, and smoothelin, and had variable expression of actin and CD10. Nonvascular smooth muscle cells of the bladder were consistently positive for smooth muscle actin, actin, desmin, and caldesmon, and consistently negative for CD10. In contrast to smooth muscle cells of the muscularis propria, which displayed strong smoothelin expression in all 15 cases, the smooth muscle cells of the muscularis mucosae displayed moderate smoothelin expression in only 1 (9%) of 11 cases (P=10(-7)). Surprisingly, although strongly highlighting endothelial and endomysial cells, the smooth muscle cells of the muscularis propria weakly expressed vimentin in only 1 (7%) of 15 cases, whereas smooth muscle cells of the muscularis mucosae had moderate or strong expression in 9 (82%) of 11 cases (P=0.00016). The sensitivity and specificity of desmin or caldesmon expression for smooth muscle cells were 100%. The sensitivity and specificity of strong smoothelin expression for muscularis propria were 100%, whereas those of absent vimentin expression were 93 and 82%, respectively. Although morphology remains the gold standard, the findings suggest that immunohistochemistry, using a panel composed of desmin, smoothelin, and vimentin, may be potentially useful for staging of bladder carcinoma. Confirmatory larger-scale studies, especially on transurethral resection specimens, are warranted.

Detection of circulating tumor cells in bladder cancer patients

The methods employed for the detection of circulating bladder cancer cells (CBCs) and their use as a molecular staging tool in clinical settings are thoroughly reviewed. CBC isolation and enrichment methods are discussed according to their advantages and pitfalls along with the clinical data of PCR-based techniques used for CBC detection. In addition, we review the specificity of molecular markers that have been proposed so far for CBC identification, and we comment on the controversial clinical data, proposing laboratory approaches which may improve the clinical significance of CBC detection in bladder cancer.

Best practice in diagnostic immunohistochemistry: prostate carcinoma and its mimics in needle core biopsies

CONTEXT

The unrelenting challenge encountered when differentiating limited-volume prostate carcinoma and sometimes subtle variants from its many morphologic mimics has increased the use of ancillary immunohistochemistry in routine prostate needle biopsies. The availability of prostate cancer-associated and basal cell-associated markers has been an invaluable addition to diagnostic surgical pathology.

OBJECTIVE

To review commonly used immunohistochemical stains, including innovative combinations, for confirmation or differential diagnosis of prostate carcinoma, and to propose appropriately constructed panels using morphologic patterns in prostate needle biopsies.

DATA SOURCES

These best practices are based on our experience with routine and consultative case sign-outs and on a review of the published English-language literature from 1987 through 2008.

CONCLUSIONS

Basal cell-associated markers p63, high-molecular-weight cytokeratin 34 beta E12, cytokeratin 5/6 or a cocktail containing p63 and high-molecular-weight cytokeratin 34 beta E12 or cytokeratin 5/6 and prostate carcinoma-specific marker alpha-methylacyl coenzyme A (coA) racemase alone or in combination are useful adjuncts in confirming prostatic carcinoma that either lacks diagnostic, qualitative or quantitative features or that has an unusual morphologic pattern (eg, atrophic, pseudohyperplastic) or is in the setting of prior treatment. The combination of alpha-methylacyl coA racemase positivity with negative staining for basal cell-associated markers supports a malignant diagnosis in the appropriate morphologic context. Dual chromogen basal cell- associated markers (p63 [nuclear] and high-molecular-weight cytokeratin 34 beta E12/cytokeratin 5/6 [cytoplasmic]) and alpha-methylacyl coA racemase in an antibody cocktail provide greater sensitivity for the basal cell layer, easing evaluation and minimizing loss of representation of the focal area interest because the staining is performed on one slide. In the posttreatment setting, pancytokeratin facilitates detection of subtle-treated cancer cells. Prostate-specific antigen and prostatic acid phosphatase markers are helpful in excluding secondary malignancies involving the prostate, such as urothelial carcinoma, and occasionally in excluding nonprostatic benign mimickers, such as nephrogenic adenoma, mesonephric gland hyperplasia, and Cowper glands. There is no role for ordering immunohistochemistry prospectively in all cases of prostatic needle biopsies.

Application of Immunohistochemistry to the Genitourinary System (Prostate, Urinary Bladder, Testis, and Kidney)

Context.—The variety of morphologic patterns of different entities of the genitourinary tract can present a diagnostic dilemma for the pathologist. This is especially true in cases of mimics of cancer, a cancer of unknown primary, or poorly differentiated tumors, in which it is hard to assign histogenesis needed to plan the correct therapy for the patient. Immunohistochemistry offers a better capacity than hematoxylin-eosin staining alone to differentiate human tissue types. Also, in the past decades, several techniques had been developed to differentiate between benign and malignant processes with morphologic overlap. By using immunohistochemistry in selected cases, the rate of false-negative and false-positive diagnoses can be reduced, and some patients are afforded the opportunity to get more specific or effective therapy as a result.

Objective.—For each subgroup of genitourinary system tumors, common diagnostic problems are reviewed, and immunohistochemical markers useful in addressing these problems are discussed, along with expected patterns of immunoreactivity.

Data Sources.—The pertinent literature, with focus on immunohistochemical staining of tumors of the genitourinary tract.

Conclusions.—The addition of immunohistochemistry to the diagnostic armamentarium for genitourinary pathologic diagnosis has increased the sensitivity and specificity of diagnoses and aided in the selection of optional therapeutic regimens in selected cases.