Smoothelin immunohistochemistry is a useful adjunct for assessing muscularis propria invasion in bladder carcinoma

Analysis of Tumor Depth Invasion With Anti-Smoothelin Antibody in Equivocal Transurethral Resection of Urinary Bladder Tumor Surgical Specimens

OBJECTIVE

To examine the expression and value of the smoothelin marker in control cases, to standardize the working method, and to analyze its application in pathologic staging process of problematic transurethral resection of bladder tumor (TURBT) cases.

MATERIAL AND METHODS

Immunohistochemical (IHC) staining was performed on tumor-free bladder wall sections, tumor-free large bowel sections, TURBTs with unequivocal tumor stage, and TURBTs with equivocal stage. The IHC staining of muscularis mucosa (MM), muscularis propria (MP), and blood vessels was evaluated semiquantitatively.

RESULTS

Smoothelin IHC staining pattern ranged from negative (30% to 67% cases) to 2+ (0% to 15% cases) in MM and from 1+ (10% to 50% cases) to 3+ (9% to 48% cases) in MP. When compared on the same slide, the smoothelin expression of MP showed a stronger staining intensity than the one of the MM in all the analyzed cases. Blood vessel muscle cells stained in a constant intensity as the MM (r = 0.9808; r = 0.9604). Smoothelin determined restaging of 33% of the problematic TURBT cases.

CONCLUSION

Smoothelin is an IHC marker that shows differential staining between coexistent MM and MP; however, variations in staining intensity and pattern may occur, aspects that can be influenced by different technique variables. We recommend using this marker as a diagnostic tool in problematic TURBT cases only when there is sufficient experience in control cases with this antibody.

pT1 high-grade bladder cancer: histologic criteria, pitfalls in the assessment of invasion, and substaging

Most patients with bladder carcinoma are diagnosed with non-muscle-invasive disease, stage Ta, and pT1. Stage remains as the single most important prognostic indicator in urothelial carcinoma. Among the pT1 bladder cancer patients, recurrence and progression of disease occur in 50% and 10%, respectively. The identification of high-risk patients within the pT1 subgroup remains an important clinical goal and an active field of research. Substaging of pT1 disease has been claimed as important histologic discriminator by the 2016 World Health Organization (WHO) classification of the genitourinary tract tumors and by the 8th edition of the American Joint Committee on Cancer (AJCC) staging manual supporting its implementation in clinical practice. Interobserver variation in pT1 diagnosis and the associated pitfalls in pT1 assessment are the critical pathological issues. The aim of this review paper is to provide the practicing pathologist with the state of the art of morphological and immunohistochemical features useful for the diagnosis of early invasive bladder carcinomas, including practical clues on how to avoid relevant interpretative pitfalls, and to summarize the current status of pT1 substaging.

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.

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.

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.