Introduction

Rare histotypes represent almost 10% of bladder tumors, more often represented within large and muscle invasive transitional cell carcinomas of the bladder (MIBC). Neoadjuvant chemotherapy is recommended (Grade A) by international guidelines. Rare histological variants, more aggressive and less responsive to systemic chemotherapy might remain unrecognized at initial transurethral resection (TURBT) in everyday clinical practice. We investigated the accuracy of TURBT in detecting rare histological variants in patients with large bladder tumors candidate to cystectomy.

Methods

The clinical and pathologic data of 540 patients submitted to TURBT and/or cystectomy for bladder cancer between Jan. 2010 and Oct. 2016, were reviewed. The presence of uncommon histotypes within urothelial bladder carcinoma has been assessed. Rare variants were diagnose according WHO criteria. Standard hematoxilyn-eosin stain was adopted and further immunohistochemistry was performed. Inferential statistical analysis was performed._x000D_

Results

Out of 540 patients, 43 (7,9%) showed rare histotypes of bladder cancer. In 5 (11,6%) cases the uncommon histotypes was revealed by palliative TURBT . The remaining 38 patients were submitted to cystectomy for bladder tumors of considerable size (mean diameter 7,8 cm; range of 5-11 cm); 14 (36,8%) harbored a pT4 tumor._x000D_ The rare histotypes were: squamous carcinoma 6 (13,9%), sarcomatoid 2 (4,8%), undifferentiated 5 (11,6%), neuroendocrine 3 (6,9%), mixed 27 (62,8%). _x000D_ TUR revealed an uncommon histotypes in 26 (68,4%) cases only. _x000D_ Moreover, in 5 (23.8%) patients an additional uncommon histology not detected by previous TUR, was demonstrated in cystectomy specimens. _x000D_

Conclusions

The prognostic role of uncommon histotypes in bladder cancer is well documented. Unrecognized rare histotypes might have important therapeutic implications since possibly less responsive to neoadjuvant chemotherapy. These patients could benefit from an immediate cystectomy avoiding neo-adjuvant chemotherapy. _x000D_ The inaccuracy of TUR in everyday clinical practice in detecting uncommon variants could be explained by an inadequate sampling of large tumors. The &[Prime]pre-cystectomy&[Prime] TUR is often performed only to confirm the infiltration. As a matter of fact, the pathologists might not receive an adequate amount of tissue. To standardize the TURBT strategy including sampling of different areas of bulky tumors could be of clinical value in patients undergoing neoadjuvant chemotherapy._x000D_ _x000D_

Funding

none