The pathologist's role in the detection of rare variants of bladder cancer and analysis of the impact on incidence and type detection

BACKGROUND: Histology is one of the most important factors determining the prognosis of bladder cancers and rare variants are generally associated with decreased disease specific survival compared to pure transitional cell carcinomas. We believe that rare bladder cancer variants are likely underdiagnosed in the absence of a dedicated uro-pathologist in many centers. The objective of this study is to evaluate the contribution of a dedicated uro-pathologist on the identification of rare bladder cancer variants. METHODS: We retrospectively analyzed the clinical and histological records of all patients which underwent a radical cystectomy and lymph node dissection between January 2000 and September 2015. The sample was divided in two groups: Group A, consists of patients who underwent radical cystectomy in the absence of a dedicated uro-pathologist at our institution, whereas the Group B consists of patients who underwent surgery when a dedicated uro-pathology service was available. We then evaluated the impact of a dedicated uro-pathologist on rare variants detection. RESULTS: One hundred thirty-seven out of 551 (24.9%) of patients who underwent RC had at least one rare variant. In Group A 38/238 (16%) of patients showed a rare variant, while 99/313 (31.6%; P<0.001) in group B. Furthermore, the diagnosis of sarcomatoid variant was statistically significantly less common in group A (P=0.0026). The concordance between final radical cystectomy histology and previous transurethral resection of bladder tumor (TURBT) histology was poor in both groups (overall 50.4%). CONCLUSIONS: The presence of a dedicated urological anatomical pathologist is of paramount importance and significantly increases the detection rate of non-transitional cell carcinoma bladder cancer types, but it does not increase the concordance rate between histological diagnoses in TURBT and radical cystectomy specimens.