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

The applicability and utility of immunohistochemical biomarkers in bladder pathology

Urinary bladder specimens are frequently encountered in the daily practice of surgical pathologists. The spectrum of pathologic entities encountered in bladder specimens is extraordinarily broad, and in some instances, immunohistochemical stains are used to help characterize challenging bladder lesions. Cost-effective biomarker selection tailored to the differential diagnosis facilitates an accurate diagnosis. This comprehensive review is prepared as a reference guide for the use of immunohistochemistry to categorize primary and secondary bladder neoplasms and to evaluate metastatic cancers for possible bladder origin.

GATA-3 Expression in all Grades and Different Variants of Primary and Metastatic Urothelial Carcinoma

Urothelial carcinoma has a varied and wide histological spectrum posing a diagnostic challenge in H&E examination alone. Immunohistochemical markers like GATA-3 along with other appropriate panel of IHC can be used. However, the percentage positivity and its intensity may vary in different variants and grades of primary and metastatic urothelial carcinoma. To observe the GATA-3 expression patterns in all the grades and different variants of primary and metastatic urothelial carcinomas. It is a prospective and retrospective observational study. All the clinically suspected urothelial carcinoma (UC) during January 2016 to December 2017 were included in the study. Depending on the differential diagnosis considered, immunohistochemistry (IHC) markers including CK7, CK20, p63, AMACR, CDX2, and p16 were done to differentiate UC from other primary carcinomas. The tumors confirmed as UC were analyzed further for GATA-3 expression by Chi-square test. The number of UC in the present study was 126 including 122 (bladder in 107, ureter in 7, renal pelvis in 5, and urethra in 3) primary and 4 metastatic UC (3 in lung and 1 in liver). Age of the patients ranged from 29 to 80 (mean 61.28) years with male/female ratio 4:1. GATA-3 showed positivity in 97 (79.5%) primary UC. GATA-3 was positive in all normal urothelium and non-invasive UC (100%), while it was positive in 69/94 (73.4%) invasive UC including variants. GATA-3 was positive in 35/39 LP invasive (89.74%) and 34/55 (61.81%) MP invasive UC. GATA-3 was positive in 39/40 papillary cases (97.5%) and 45/59 (76.27%) cases of non-papillary UC. GATA-3 showed strong expression in all metastatic UC (100%). GATA-3 expression was seen in 101/126 (80.15%) of UC including primary and metastatic carcinomas and hence was a useful marker in diagnosing UC. The GATA-3 positivity decreased from normal urothelium to UC; low-grade UC to high-grade UC; non-invasive to invasive UC; lamina propria invasive to muscle invasive UC; papillary to non-papillary UC.

Dataset for the reporting of carcinoma of the bladder-cystectomy, cystoprostatectomy and diverticulectomy specimens: recommendations from the International Collaboration on Cancer Reporting (ICCR)

The International Collaboration on Cancer Reporting (ICCR) is a not for profit organisation whose goal is to produce standardised internationally agreed and evidence-based datasets for pathology reporting. With input from pathologists worldwide, the datasets are intended to be uniform and structured. They include all items necessary for an objective and accurate pathology report which enables clinicians to apply the best treatment for the patient. This dataset has had input from a multidisciplinary ICCR expert panel. The rationale for some items being required and others recommended is explained, based on the latest literature. The dataset incorporates data from the World Health Organization (WHO) 2016, and also from the latest (8th edition) TNM staging system of the American Joint Committee on Cancer (AJCC). Fifteen required elements and eight recommended items are described. This dataset provides all the details for a precise and valuable pathology report required for patient management and prognostication. This dataset is intended for worldwide use, and should facilitate the collection of standardised comparable data on bladder carcinoma at an international level.

Skeletal Muscle Metastasis to Vastus Lateralis from a Urothelial Carcinoma: A Case Report and Review of Its Diagnosis and Management

Bladder cancer is a common genitourinary tract malignancy. Urothelial carcinoma is the most frequent type of bladder cancer and it commonly metastasises to lymph nodes, bone, lung and liver by a haematogenous route. Skeletal metastases are very rare and are usually present in patients with advanced metastatic disease. We present an unusual case of a 71-year-old male with a urothelial carcinoma metastasis to the vastus lateralis muscle 3 months following a cystoprostatectomy for muscle invasive bladder cancer.

Assessment of Histopathological Parameters Useful in the Diagnosis of Low Grade Non-Invasive Urothelial Carcinomas

Urothelial papillary lesions of urinary bladder are frequent lesions in medical practice and sometimes difficult to be histopathologically classified. In this study were included 179 urothelial papillary lesions, represented by low grade non-invasive urothelial carcinomas (LGNIUC), papillary urothelial neoplasms of low malignant potential (PUNLMP) and urothelial papillomas (UP), for which the architectural and cytological histopathological parameters were analyzed in order to determine their usefulness for the classification of lesions. For each parameter, an aggressivity score was set, the sum representing the composite histological score (CHS) for each case. The increase of urothelial thickness, the papillae fusion, the loss of cellular polarity, loss of basal cell palisading and absence of umbelliform cells were commonly associated with diffuse pattern in LGNIUC, were focal/absent in PUNLMP and absent in UP. The nuclear hypertrophy and hyperchromasia, the nucleoli presence and mitotic activity were specific for LGNIUC, rarely associated with PUNLMP and absent/low in UP. CHS values for the three categories of analyzed lesions were superior statistically significant in LGNIUC compared to PUNLMP and UP. The mitotic index and the thickness of cytological atypical epithelial layers support the parameters utility as reproducible criteria for the differentiation of papillary urothelial tumors.

Case - Highly aggressive urothelial carcinoma of the bladder presenting with solitary metastasis to the phalanx

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Urothelial Carcinoma In Situ (CIS): New Insights

Urothelial carcinoma in situ (CIS) is a high-grade noninvasive malignancy with a high tendency of progression. Although it is typically grouped with other nonmuscle invasive bladder cancers, its higher grade and aggressiveness make it a unique clinical entity. Urothelial CIS is histologically characterized by replacement of the urothelium by cells which fulfill the morphologic criteria of malignancy including nuclear pleomorphism, hyperchromasia, prominent nucleoli, and increased numbers of normal and abnormal mitoses. Urothelial CIS may be categorized as primary when it is not associated with any past or present urothelial carcinoma. It is termed as secondary when there is concomitant or previous urothelial carcinoma in the patient. In recent years detailed molecular studies have provided valuable data for intrinsic molecular subclassification of urothelial carcinoma into 2 broad categories namely luminal and basal types with significant implications for prognosis and therapy. Similar studies on urothelial CIS are limited but have provided crucial insight into the molecular basis of CIS. These studies have revealed that urothelial CIS may also be divided into luminal and basal subtypes, but luminal subtype is much more common. It has also been shown that in many cases, luminal type of urothelial CIS may undergo a class switch to basal type during progression to an invasive carcinoma. Additional studies may be required to confirm and further elaborate these findings.

The enhanced expression of estrogen-related receptor α in human bladder cancer tissues and the effects of estrogen-related receptor α knockdown on bladder cancer cells

Estrogen-related receptor α (ERRα) belongs to the superfamily of nuclear orphan receptors. However, the role of ERRα in bladder cancer remains unknown. This study examined the expression of ERRα in bladder cancer tissues and explored the molecular mechanisms of ERRα in bladder cancer progression. The expression of ERRα in bladder cancer tissues from 61 patients was determined by immunohistochemistry. We performed quantitative real-time polymerase chain reaction assay to detect the gene expression levels and carried out Western blot assay to measure protein levels. In vitro functional assays, including colony formation, Cell Counting Kit-8, Transwell invasion, and migration assays, were performed to detect bladder cancer cell growth, proliferation, invasion, and migration, respectively. Flow cytometry was used to determine the cell apoptotic rate of bladder cancer cells. Among the 61 detected bladder cancer tissues, 39 bladder cancer tissues showed positive ERRα immunoreactivity. Higher ERRα immunoreactivity score was significantly associated with TNM stage, tumor grade, distant metastasis, and poor survival in patients with bladder cancer. Univariate and multivariate analyses showed that ERRα immunoreactivity was an independent prognostic factor for overall survival in patients with bladder cancer. ERRα was found to be upregulated in bladder cancer cell lines, and knockdown of ERRα suppressed bladder cancer cell growth, proliferation, invasion, and migration; promoted bladder cancer cell apoptosis; and inhibited the epithelial-mesenchymal transition of bladder cancer cells. On the other hand, bladder cancer cell proliferation, invasion, and migration were significantly enhanced after cells were transfected with an ERRα-overexpressing vector. In vivo tumor growth and metastasis assays showed that ERRα knockdown resulted in remarkable inhibition of tumor growth and tumor metastasis in nude mice. Collectively, our results suggest that the enhanced expression of ERRα may play a key role in the development and progression of bladder cancer and ERRα may serve as an important prognostic factor for bladder cancer.

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.

Identification of Significant Prognostic Tissue Markers Associated with Survival in Upper Urinary Tract Urothelial Carcinoma Patients Treated with Radical Nephroureterectomy: A Retrospective Immunohistochemical Analysis Using Tissue Microarray

Purpose

The purpose of this study was to identify prognostic tissue markers for several survival outcomes after radical nephroureterectomy among patients with upper urinary tract urothelial carcinoma using tissue microarray and immunohistochemistry.

Materials and Methods

Retrospectively, data of 162 non-metastatic patients with upper urinary tract urothelial carcinoma after radical nephroureterectomy between 2004 and 2016 were reviewed to determine intravesical recurrence-free survival (IVRFS), disease-free survival (DFS), and overall survival (OS). The expression of 27 tissue markers on a tissue microarray of radical nephroureterectomy samples and prognostic values of clinicopathological parameters were evaluated using immunohistochemistry and Cox proportional hazard models after adjusting for significant prognostic clinicopathological variables. The expression of all tissue markers was categorized into a binary group with continuous H-scores (0-300).

Results

Median follow-up was 53.4 months (range, 3.6 to 176.5 months); and, 58 (35.8%), 48 (29.6%), and 19 (11.7%) bladder recurrence, disease progression, and all cause death, respectively, were identified. After adjusting for significant clinicopathological factors including intravesical instillation for bladder recurrence-free survival, pathologic T category and intravesical instillation for disease progression-free survival, and pathologic T category for OS (p < 0.05), IVRFS was associated with epithelial cadherin (hazard ratio [HR], 0.49), epidermal growth factor receptor/erythroblastosis oncogene B (c-erb) (HR, 2.59), and retinoblastoma protein loss (HR, 1.85); DFS was associated with cyclin D1 (HR, 2.16) and high-molecular-weight cytokeratin (HR, 0.42); OS was associated with E-cadherin (HR, 0.34) and programmed cell death 1 ligand (HR, 13.42) (p < 0.05).

Conclusion

Several significant tissue markers were associated with survival outcomes in upper urinary tract urothelial carcinoma patients treated with radical nephroureterectomy.

Clinical significance of urothelial carcinoma ambiguous for muscularis propria invasion on initial transurethral resection of bladder tumor

PURPOSE

To evaluate the clinical significance of invasive urothelial carcinoma that is ambiguous for muscularis propria invasion on initial transurethral resection of bladder tumor (TURBT).

METHODS

All consecutive in-house TURBTs with invasive urothelial carcinoma from 1999 to 2017 that underwent radical cystectomy (RC) were grouped as follows: invasion of the lamina propria (INLP; n = 102; 24%), invasion of muscularis propria (INMP; n = 296; 69%) and ambiguous for muscularis propria invasion (AMP; n = 30; 7%). AMP was defined as extensive invasive carcinoma displaying thin muscle bundles where it is difficult to determine with certainty if those muscle bundles represent muscularis mucosae or muscularis propria (detrusor). Cases with any amount of small cell carcinoma or prior therapy were excluded.

RESULTS

The average age was 66 years in INLP, 67 years in INMP, and 65 years in AMP. RC showed invasive carcinoma stage pT2 or above in 50/102 (49%) of INLP vs. 255/296 (86%) of INMP (P ≤ 001) vs. 25/30 (83.33%) of AMP (P = 0.002). Lymph nodes showed metastatic carcinoma in 18/98 (18.36%) of INLP vs. 96/272 (35.29%) of INMP (P = 0.002), and 6/25 (24%) in AMP (P = 0.729). The average follow-up was 48 months (range 0-192). Survival of AMP patients was similar to INLP and both were significantly better than INMP (P = 0.002 and P = 0.016).

CONCLUSION

The great majority of patients with AMP on initial TURBT have advanced disease on RC and emphasizes the need for early repeat TURBT or even consideration of early cystectomy to lower the risk of worse pathological findings and to prolong survival.

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.

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.

Unclassified renal cell carcinoma: diagnostic difficulties and treatment modalities

Over the past few decades, the classification system of renal cell carcinoma (RCC) variants has witnessed tremendous and ongoing refinement driven by genomic profiling and morphological correlation that have provided valuable insights into tumor biology and characterization of this heterogeneous subset of tumors. The importance of accurate classification cannot be understated given the downstream impact on treatment decisions, risk stratification, and need for genetic testing. While the morphologic heterogeneity across these tumors is increasingly being recognized, all non-clear-cell RCCs are commonly categorized under one therapeutic category with management strategies that largely derive from clear-cell RCCs. As research in metastatic RCC progresses, there is a growing focus on rare subtypes and unclassified tumors, which is rapidly changing the treatment paradigm for non-clear-cell RCC. This review focuses on the histomorphologic diagnostic challenges of unclassified RCCs discussing the utility of contemporary diagnostic tools. It further discusses the current state of knowledge and guidelines for management of this class of tumors.

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.

A practical diagnostic approach to hepatic masses

The differential diagnosis of hepatic mass lesions is broad and arriving at the right diagnosis can be challenging, especially on needle biopsies. The differential diagnosis of liver tumors in children is different from adults and is beyond the scope of this review. In adults, the approach varies depending on the age, gender, and presence of background liver disease. The lesions can be divided broadly into primary and metastatic (secondary), and the primary lesions can be further divided into those of hepatocellular origin and nonhepatocellular origin. The first category consists of benign and malignant lesions arising from hepatocytes, while the second category includes biliary, mesenchymal, hematopoietic, and vascular tumors. Discussion of nonepithelial neoplasms is beyond the scope of this review. The hepatocytic lesions comprise dysplastic nodules, focal nodular hyperplasia, hepatic adenoma, and hepatocellular carcinoma, and the differential diagnosis can be challenging requiring clinicopathological correlation and application of immunohistochemical (IHC) markers. Liver is a common site for metastasis, sometimes presenting with an unknown primary site, and proper workup is the key to arriving at the correct diagnosis. The correct diagnosis in this setting requires a systematic approach with attention to histologic features, imaging findings, clinical presentation, and judicious use of IHC markers. The list of antibodies that can be used for this purpose keeps on growing continually. It is important for pathologists to be up to date with the sensitivity and specificity of these markers and their diagnostic role and clinical implications. The purpose of this review is to outline the differential diagnosis of hepatic masses in adults and discuss an algorithmic approach to make a right diagnosis.

Mesenchymal Neoplasms of the Genitourinary System: A Selected Review with Recent Advances in Clinical, Diagnostic, and Molecular Findings

Mesenchymal neoplasms of the genitourinary (GU) tract often pose considerable diagnostic challenges due to their wide morphologic spectrum, relative rarity, and unexpected incidence at GU sites. Soft tissue tumors arise throughout the GU tract, whether from adventitia surrounding or connective tissues within the kidneys, urinary bladder, and male and female genital organs. This selected article focuses on a subset of these lesions, ranging from benign to malignant and encompassing a range of patterns of mesenchymal differentiation, where recent scholarship has lent greater insight into their clinical, molecular, or diagnostic features.

SIU-ICUD on bladder cancer: pathology

Many changes have been made during these last years and concepts for understanding bladder cancer have evolved. We make an update with the latest findings of the WHO (World Health Organistaion) 2016, ICCR (International Collaboration on Cancer Reporting) and other official organisms and try to show the latest developments. In this document we provide new consensus guidelines and insights. We kept this document short and concise providing consensus guidelines to clinicians for the best patient care, it should be easy to understand for a non pathologists. We focussed on several burning issues, such as the anatomical and histological understanding of the bladder wall, the prognostic significance of grading and the most challenging problems in staging, we underline our needs from the clinicians such as clinical information, we further discuss the histological subtypes of bladder cancer, which is an extremely important issue in the light of molecular classifications and give prognostic insights. Furthermore, we discuss the ICCR worldwide consensus reporting, urinary cytology with the Paris system and several issues such as frozen section specimen.

Urinary Bladder Pathology: World Health Organization Classification and American Joint Committee on Cancer Staging Update

Context.—

Since the publication of the previous World Health Organization (WHO) Classification of Tumours on the Pathology and Genetics of Tumours of the Urinary System and Male Genital Organs in 2004, significant new knowledge has been generated regarding the pathology and genetics of bladder neoplasia. Publication of the 2016 WHO “Blue Book” has codified that new data into updated recommendations for classification and prognostication. Similarly, the recent release of the 8th edition of the American Joint Committee on Cancer (AJCC) Cancer Staging Manual, which was implemented in January 2018, has also addressed staging criteria for bladder cancer in several unique settings to clarify their application.

Objective.—

To highlight subtle changes within the recent WHO and AJCC publications that may affect daily surgical pathology practice.

Data Sources.—

Peer-reviewed published literature, the 2016 WHO Classification of Tumours of the Urinary System and Male Genital Organs, and the 8th edition of the AJCC Cancer Staging Manual were reviewed.

Conclusions.—

Selected changes and/or clarifications are discussed and include classification of flat and papillary urothelial neoplasia, select variant patterns of invasive urothelial carcinoma, staging of invasive carcinoma in bladder diverticula, and staging of carcinomas involving the prostate gland.

Immunohistochemistry for Diagnosis of Metastatic Carcinomas of Unknown Primary Site

Immunohistochemistry has become an essential ancillary examination for the identification and classification of carcinomas of unknown primary site (CUPs). Over the last decade, the diagnostic accuracy of organ- or tumour-specific immunomarkers and the clinical validation of effective immunohistochemical panels has improved significantly. When dealing with small sample sizes, diagnostic accuracy is crucial, particularly in the current era of targeted molecular and immune-based therapies. Effective systematic use of appropriate immunohistochemical panels enables accurate classification of most of the undifferentiated carcinomas as well as careful preservation of tissues for potential molecular or other ancillary tests. This review discusses the algorithmic approach to the diagnosis of CUPs using CK7 and CK20 staining patterns. It outlines the most frequently used tissue-specific antibodies, provides some pitfalls essential in avoiding potential diagnostic errors and discusses the complementary tools, such as molecular tumour profiling and mutation-specific antibodies, for the improvement of diagnosis and prediction of the treatment response.

Urothelial tumors with villous morphology: Histomorphology and role of immunohistochemistry in diagnosis

Villous adenoma and urothelial carcinoma with villoglandular differentiation (UCVGD) are rare urothelial tumours showing villous morphology, the former being a preneoplastic entity and the latter being a malignant one. The detailed immunohistochemistry of these entities is previously not described in the literature. Moreover, a limited biopsy sample of UCVGD or a villous adenoma with or without adenocarcinoma may be difficult to distinguish on the basis of the histomorphology alone. An immunohistochemical panel comprising of GATA3, p63, β-catenin, CK7 and CK20 was performed on five cases of UCVGD and three cases of villous adenoma with the aim of studying the expression of the proteins thereby aiding in the diagnosis of these entities in a limited surgical pathology specimen. The mean age of UCVGD was 66.8 years and all the patients were male. All the cases of UCVGD were associated with high grade papillary urothelial carcinoma with lamina propria invasion. The immunohistochemical panel showed strong nuclear GATA3 expression in the urothelial component of UCVGD. Interestingly, the high grade and the low grade villoglandular components of UCVGD also expressed GATA3 (nuclear) with a progressive loss of expression from the high grade to the low grade component. The villous adenomas showed negativity or aberrant cytoplasmic positivity for GATA3. The β-catenin showed a gradual loss of membranous expression from villous adenoma to low grade and high grade villoglandular components of UCVGD with a patchy membranous expression in the urothelial component of the UCVGD. p63 showed strong nuclear positivity in the urothelial component and uniform negativity in the villous adenoma and villoglandular component of UCVGD irrespective of its grade, thereby distinguishing the villoglandular component from the urothelial component. The urothelial component of UCVGD showed strong membranous CK7 expression and was higher than the CK20 expression in the urothelial component. In contrast, CK20 expression was higher in villous adenoma as compared to CK7. There was no difference in the expression of CK7 and CK20 in the villoglandular components and low grade and high grade villoglandular areas. The above-mentioned immunohistochemical pattern may help to distinguish the UCVGD from the villous adenoma.

Differential expression of cytokeratin 14 and 18 in bladder cancer tumorigenesis

It has been previously suggested that cytokeratins (CKs) are important diagnostic and prognostic biomarkers for urothelial lesions. Hence it is imperative to understand the expression pattern of cytokeratins during formation of papillary bladder cancer, which was the objective of the current study. Expression pattern of CK14 and CK18 were examined using immunohistochemical staining in a mice model of papillary bladder cancer. Twenty female mice were divided into two groups-group 1 (NT) and group 2, which received N-butyl- N-(4-hydroxybutyl) nitrosamine (BBN) for 20 weeks plus one week without treatment. Following histological classification of bladder lesions, CK14 and CK18 immunostaining was assessed according to its distribution and intensity. In NT animals, both basal cells and umbrella cells showed sporadic positive staining for CK14 and CK18, respectively. In BBN group, hyperplastic lesions showed significantly more CK14 and significantly less CK18 staining ( P < 0.05 in each case). Invasive carcinomas showed increased CK14 immunostaining in all epithelial layers. Cumulatively, our data indicate that altered CK14 (high) and CK18 (low) expression is perhaps an early event in bladder cancer tumorigenesis in females at least and is characteristic of both urothelial superficial pre-neoplastic and neoplastic lesions. Impact statement Studies have shown that expression of cytokeratins (CKs) or their altered distribution affects the bladder cancer pathogenesis and disease outcome, while the underlying mechanisms are not clear. The present study aims to explore the expression pattern of CK14 and CK18 during formation of papillary bladder cancer. The results showed that hyperplastic lesions showed significantly more CK14 and significantly less CK18 staining and invasive carcinomas showed increased CK14 immunostaining in all epithelial layers in N-butyl- N-(4-hydroxybutyl)nitrosamine (BBN)-induced mouse model. The results indicate that altered CK14 (high) and CK18 (low) expression is perhaps an early event in bladder cancer tumorigenesis and is characteristic of both urothelial superficial pre-neoplastic and neoplastic lesions, which may provide the early diagnosis index.

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.

Mucinous and secondary tumors of the prostate

Primary mucinous tumors and secondary tumors involving the prostate gland are relatively uncommon, however they have important diagnostic, therapeutic, and prognostic implications. The primary mucinous tumors of the prostate include mucinous (colloid) adenocarcinoma of the prostate, prostatic adenocarcinoma with mucinous features, and mucinous adenocarcinoma of the prostatic urethra (mucin-producing urothelial-type adenocarcinoma of the prostate). Mucinous adenocarcinoma of the prostate is defined as a primary prostatic acinar tumor characterized by the presence of at least 25% of the tumor composed of glands with extraluminal mucin. This diagnosis can only be made in radical prostatectomy specimens. Recent studies have shown that these tumors have a similar or in some cases better prognosis than conventional prostatic adenocarcinoma treated by radical prostatectomy. The preferred terminology for tumors that are composed of <25% extraluminal mucinous component in radical prostatectomy specimens is 'prostatic adenocarcinoma with mucinous features.' All cases of prostatic adenocarcinoma with extraluminal mucinous components in prostate needle core biopsies or transurethral resection of the prostate specimens are also referred to as 'prostatic adenocarcinoma with mucinous features.' Mucinous adenocarcinoma of the prostatic urethra (mucin-producing urothelial-type adenocarcinoma of the prostate) as the name implies, does not arise from prostatic acini or ducts, and is a distinct entity that arises from the prostatic urethra usually from urethritis glandularis or glandular metaplasia with malignant transformation, and is analogous to adenocarcinoma with mucinous differentiation arising from the urinary bladder. This tumor is aggressive and has a relatively poor prognosis. The most common secondary tumors that arise from adjacent organs and spread (direct extension or metastasis) to the prostate gland, include urothelial carcinoma of the bladder and colorectal adenocarcinoma. Other secondary tumors that may involve the prostate include metastatic epithelial tumors from several other sites, malignant melanoma and soft tissue tumors.

Secondary Malignancies of the Bladder: Avoiding the Diagnostic Pitfall

Although rare, secondary tumors of the bladder can present a diagnostic dilemma to pathologists considering a differential diagnosis of primary bladder cancer. We investigated the clinicopathologic and imaging characteristics of metastatic tumors to the bladder. We retrospectively reviewed the surgical pathology databases from 2 sites from 2013 to 2016, identifying 66 cases of secondary bladder tumors. Clinical, pathologic, and imaging findings were reviewed. Mean age at diagnosis was 63 years (range = 25-87). Females had a significantly higher proportion (44/66, 66.7%) of secondary bladder tumors compared with males (22/66, 33.3%; P = .007). In total, 56/66 (84.8%) patients had a clinical history of an in situ or invasive malignancy in another organ, and 54/66 (81.8%) patients had imaging supporting a metastatic tumor. Only 2/66 (3.0%) patients had a prior history of urothelial carcinoma. In total, 4/66 (6.1%) cases (all females) were originally misdiagnosed as primary bladder malignancies and were corrected after clinicoradiologic correlation. Overall, colorectal origin was most common (15/66, 22.7%), followed by cervical and ovarian primaries (10/66, 15.2% each). Cervical and ovarian origins predominated in the female cohort (10/44, 22.7% each), followed by endometrial (8/44, 18.2%). Colorectal and prostate primaries were the most common among males (10/22, 45.5%, and 7/22, 31.8%, respectively). Secondary bladder tumors can mimic urothelial carcinomas. In our cohort, gynecological, colorectal, and prostatic origins were most common. Clinical history, imaging, and immunohistochemical studies can be useful in avoiding this diagnostic pitfall.

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.

Second Opinion Expert Pathology Review in Bladder Cancer: Implications for Patient Care

Objectives. To review bladder specimens referred to our facility for secondary review to determine the frequency and degree of changes in pathological diagnoses, which could affect patient care. Methods. A retrospective review of 246 bladder specimens sent to our pathology department for second opinion pathological review was performed. All consultation specimens were reviewed by a single genitourinary (GU)-subspecialized surgical pathologist. Any changes in the pathological grade, stage, or histological tumor type were noted as well as patient demographic data. Statistical analysis was performed to determine the frequency and type of discrepancies in diagnoses and determine any associations with patient demographic parameters. Results. Secondary pathology consultation of 246 bladder specimens from 233 patients were reviewed and compared with the primary diagnosis. The diagnosis was altered in 91/246 cases (37.0%). The number of cases reviewed per patient and specimen type was not associated with a change in diagnosis ( P = .19; P = .1). Of the cases with a change in diagnosis, 8 (8.8%) changed malignancy status, 46 (50.5%) changed stage, 16 (17.6%) changed tumor type (ie, change from urothelial carcinoma to prostate adenocarcinoma), 16 (17.6%) changed histological variant subtype, and 14 (15.4%) changed grade. There was no association noted between age, gender, or race and changes in diagnosis ( P = .53; P = .41; P = .70). Conclusions. Secondary pathology review with a GU-subspecialized surgical pathologist can change the stage, grade, or histological subtype on bladder biopsy and tumor resection specimens in more than one-third of cases. Age and gender were not associated with the frequency of change in diagnosis on consultation review.

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.

Noninvasive Papillary Basal-like Urothelial Carcinoma: A Subgroup of Urothelial Carcinomas With Immunohistochemical Features of Basal Urothelial Cells Associated With a High Rate of Recurrence and Progression

BACKGROUND

We investigated the clinical and pathologic significance of a subgroup of noninvasive papillary urothelial carcinomas (UCs) expressing reactivity to urothelial basal cell markers.

DESIGN

In total, 302 consecutive cases of noninvasive papillary UC were evaluated immunohistochemically with cytokeratin 5 (CK5)/CD44. Any UC that was reactive for greater than 25% thickness of the urothelium was designated as basal-like urothelial carcinoma (BUC); remaining UC cases were designated as non-BUC. The follow-up period was up to 3 years. Historical review of UC was extended for up to 3 retrospective years.

RESULTS

Among 302 noninvasive UC, BUC was identified in 33 of 256 (12.9%) low-grade UC and 8 of 46 (17%) high-grade UC (P=0.041). Immunoreactivity for CD44 was similar to that of CK5, but displayed weaker and more diffuse staining. CK20 was reactive in 9 cases, primarily high-grade BUC. Other basal cell markers (34bE12, p63, bcl2, and EP4) were found to be neither sensitive nor specific in detecting UC with high CK5 expression. In comparison with non-BUC, BUC was associated with increased multifocality, larger tumor size, higher recurrence rate, and more frequent upgrading and stage progression. In the follow-up period of 3 years, distant metastasis occurred in 6 cases of which 5 were in the BUC subgroup.

CONCLUSIONS

Our results showed that noninvasive papillary BUC represents a small subset associated with increased risk of tumor recurrence and progression. The aggressive behavior is likely associated with basal-like features of BUC, as seen in carcinomas with basal cell features in other body sites.

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.

Level of mitoses in non-muscle invasive papillary urothelial carcinomas (pTa and pT1) at initial bladder biopsy is a simple and powerful predictor of clinical outcome: a multi-center study in South Korea

BACKGROUND

Histologic grade is the most important predictor of the clinical outcome of non-muscle invasive (Ta, T1) papillary urothelial carcinoma (NMIPUCa), but its ambiguous criteria diminish its power to predict recurrence/progression for individual patients. We attempted to find an objective and reproducible histologic predictor of NMIPUCa that correlates well with the clinical outcome.

METHODS

A total of 296 PUCas were collected from the Departments of Surgical Pathology of 11 institutions in South Korea. The clinical outcome was grouped into no event (NE), recurrence (R), and progression (P) categories. All 25 histological parameters were numerically redefined. The clinical pathology of each case was reviewed individually by 11 pathologists from 11 institutions based on the 2004 WHO criteria and afterwards blindly evaluated by two participants, based on our proposed parameters. Univariate and multivariate logistic regression analyses were performed using the R software package.

RESULTS

The level of mitoses was the most reliable parameter for predicting the clinical outcome. We propose a four-tiered grading system based on mitotic count (> 10/10 high-power fields), nuclear pleomorphism (smallest-to-largest ratio of tumor nuclei >20), presence of divergent histology, and capillary proliferation (> 20 capillary lumina per papillary core).

CONCLUSIONS

The level of mitoses at the initial bladder biopsy and transurethral resection (TUR) specimen appeared to be an independent predictor of the Ta PUCa outcome. Other parameters include the number of mitoses, nuclear pleomorphism, divergent histology, and capillary proliferation within the fibrovascular core. These findings may improve selection of patients for a therapeutic strategy as compared to previous grading systems.

Diagnostic Value of Smoothelin and Vimentin in Differentiating Muscularis Propria from Muscularis Mucosa of Bladder Carcinoma

Background

Determination of the extent of involvement or pathological staging is one of the requirements for adequate evaluation of bladder cancer specimens. Therefore, the differentiation between MP and MM is essential for proper treatment and avoiding over or under staging.

Aim

The present study aimed at evaluation of diagnostic value of smoothelin and vimentin expression both singly and in combination for differentiation between MM and MP.

Methods

This study was carried out on 59 cystectomy specimens of primary bladder carcinoma and eleven cystoscopic biopsies for non-neoplastic bladder lesions (cystitis).

Results

Histologically, MM was identified clearly in 40 cases and MP was identified in all 70 examined cases. The cases were immunostained for smoothelin and vimentin. Intensity of smoothelin expression showed significant difference (P = 0.001) between MM and MP with 97.5% sensitivity and 95% specificity and the percentage of smoothelin expression was significantly higher in MP compared to MM (P = 0.001) with 95.7% sensitivity and 85% specificity (using 65% as cut-off point). Vimentin was negative in MP and showed positive expression in 32 cases (80%) of MM with a statistical significant difference (P = 0.001) providing 80% sensitivity and 100% specificity. Combined moderate to strong smoothelin and negative vimentin offered 100% sensitivity and 100% specificity towards the identification of MP.

Conclusions

Differentiation of MM from MP can be made based on histopathological criteria, which are unfortunately overlapping in many cases. Moderate to strong smoothelin expression with negative vimentin could be very helpful procedure in difficult and overlapping cases with a high diagnostic validity.

A Rare Case of Esophageal Adenocarcinoma with Urinary Bladder Metastasis

Metastatic esophageal adenocarcinoma to the urinary bladder is extremely rare. We describe a previously healthy 49-year-old female with recent diagnosis of adenocarcinoma of the gastroesophageal junction with metastatic disease to the liver. Biopsy was positive for human epidermal growth factor receptor 2 (HER2) by Fluorescence In Situ Hybridization (FISH). She received six cycles of Cisplatin, 5-Fluorouracil, and Herceptin and subsequently developed symptomatic anemia and hematuria. Cystoscopy with retroflexion was performed and she received a transurethral resection of bladder tumor with fulguration. Pathology of the bladder tumor revealed similar morphology to her liver metastasis and immunohistochemical stains were consistent with metastatic esophageal cancer. Three weeks after being diagnosed with metachronous urinary bladder metastasis from esophageal adenocarcinoma primary, she expired. She only received her first cycle of palliative chemotherapy with Ramucirumab and Paclitaxel.

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.

Challenges in Pathologic Staging of Bladder Cancer: Proposals for Fresh Approaches of Assessing Pathologic Stage in Light of Recent Studies and Observations Pertaining to Bladder Histoanatomic Variances

The paradigm of pathologic stage (pT) categorization in bladder cancer remains the depth of invasion into the different histologic layers of the bladder wall. However, the approaches to assigning pT stage category toward an enhanced outcome stratification have been marked by challenges and innovations, due in part to our growing appreciation of the surprisingly perplexing bladder histoanatomy. Upstaging of pT1 tumors after radical cystectomy is substantial and underscores the potential value of pT1 substaging in transurethral resection (TUR) specimens. The 2017 American Joint Committee on Cancer tumor-node-metastasis system recommends pT1 substaging but recognizes the need to optimize the approach. Over the years, the cut-off for microinvasion has been significantly lowered to 0.5 mm and is now a promising scheme for pT1 (micrometric) substaging. Unlike the micrometric approach, histoanatomic substaging using muscularis mucosae (MM) and vascular plexus as landmarks is less feasible in TUR specimens and inconsistent in stratifying the outcome of pT1 tumors. The lamina propria possesses inherent variations in depth, MM, and vascular plexus dispositions that should be factored in future pT1 substaging proposals. Histoanatomic variations among the bladder regions also occur, and studies suggest that trigone and bladder neck cancers may have more adverse outcomes. The muscularis propria (MP), besides being the essential histologic landmark for assigning pT2 stage category, is also considered a surrogate for the adequacy of TUR, furthering the importance of identifying its presence in TUR specimens. MP, however, may be mimicked by hyperplastic or isolated MP-like MM muscle bundles in the lamina propria with overstaging implications, and caution should be exercised in distinguishing these 2 muscle types morphologically and immunohistochemically. Presence of additional superficial MP unique from the detrusor muscle proper may also complicate staging at the trigone and ureter insertion sites. With regard to the depth of MP invasion, large and multicenter studies have reaffirmed the prognostic significance of pT2a/b subcategories. It is revealed that there are at least 3 ways used to demarcate the irregular MP to perivesical soft tissue junction, and use of a common criterion indicates improvement in pT2b/pT3a staging reproducibility. Although studies have shown significantly poorer outcome in pT3b compared with pT3a tumors, this designation has a substantial reliance on the prosector's gross assessment of perivesical soft tissue invasion which if performed incorrectly may lead to staging inaccuracy of pT3 tumors. The 8th edition of the American Joint Committee on Cancer has updated the staging schema for bladder cancers with concomitant prostatic stromal invasion and cancers within bladder diverticula. Because of 2 possible pT designations, prostatic stromal invasion in TUR specimens should not be automatically staged as either pT4a or pT2 (urethral). Recent data support that bladder cancer invading into the seminal vesicle has comparable outcome to pT4b tumors. Interestingly, several studies in pT4a tumors, which are staged based on sex-specific organs, have shown poorer outcome in females than males after radical cystectomy, and while there are possibly several reasons, they may also include anatomic factors. Despite the progress has been made, work remains to be done to inform future bladder cancer pT category definitions and their reproducibility in application and prognostication.

Plasmacytoid Urothelial Carcinoma of the Urinary Bladder: A Clinicopathologic and Immunohistochemical Analysis of 49 Cases

OBJECTIVES

Plasmacytoid urothelial carcinoma (PUC) of the bladder is a rare histologic variant. We retrospectively analyzed a large series of bladder PUC from a single institution.

METHODS

The patients consisted of 44 men and five women with a mean age of 62 years (range, 45-86 years).

RESULTS

PUC was pure in 23 cases and mixed with other histologic types in 26 cases. All PUCs diffusely invaded the bladder wall. Most PUCs lacked immunoreactivity for the retinoblastoma (RB) gene protein (12/32) and E-cadherin (8/30). Of the 44 patients with follow-up information, 25 died of PUC at a mean of 23 months, whereas 19 patients were alive at a mean of 22 months.

CONCLUSIONS

Our findings support that bladder PUC is a highly aggressive disease. The lack of E-cadherin expression in PUCs may underlie the distinct discohesive histologic appearance, and abnormal function of the RB gene may be implicated in the development of PUC.

Immunostain use in the diagnosis of melanomas referred to a tertiary medical center: a 15-year retrospective review (2001-2015)

BACKGROUND

Little is known regarding the clinical practice of immunohistochemistry in the diagnosis of melanoma. We aimed to assess the incidence of immunostain usage by referring pathologists and dermatopathologists in melanoma cases sent for consultative review. As a secondary objective, associations between immunostain use and specific melanoma characteristics were also evaluated.

METHODS

This is a retrospective review of consultation reports of referred melanomas at a tertiary academic center in New York, NY from 2001 to 2015. Univariate regression analysis was performed on melanomas with accompanying immunostains and on characteristics such as Breslow's depth, location, prognostic factors and morphologic subtypes. Associations between immunostain usage and these characteristics were analyzed using Fisher's exact test.

RESULTS

Immunostain use significantly increased over the study period (p < 0.001) and was more likely to be associated with melanomas that were thicker [odds ratio (OR) = 2.5; 1.7-3.6]; located on the head and neck (OR = 1.6; 1.4-1.9) or acral sites (OR = 1.5; 1.1-2.0); had ulceration (OR = 2.1; 1.6-2.8), dermal mitoses (OR = 1.3; 1.1-1.5), or perineural invasion (OR = 3.6; 2.0-6.5); or were of desmoplastic (OR = 7.4; 4.5-12), amelanotic (OR = 7.1; 3.6-14), or nevoid subtypes (OR = 4.0; 1.7-8.9).

CONCLUSIONS

Immunostain use in the diagnosis of melanoma has increased significantly in the past 15 years for reasons that remain unclear.