INTRODUCTION AND OBJECTIVES: 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.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.
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%). TUR revealed an uncommon histotypes in 26 (68,4%)
cases only. Moreover, in 5 (23.8%) patients an additional uncommon
histology not detected by previous TUR, was demonstrated in cystectomy
specimens.
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.
The inaccuracy of TUR in everyday clinical practice in detecting
uncommon variants could be explained by an inadequate sampling
of large tumors. The 00pre-cystectomy00 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
