[889] Urothelial Carcinoma with Mucinous Features

F Tavora, JI Epstein. Johns Hopkins Hospital, Baltimore

Background: Variants of urothelial carcinoma include a plethora of lesions with distinct morphology and in several cases specific biological behavior. Among those, mucin expression has been reported in adenocarcinomas (micropapillary variant, intestinal type adenocarcinoma and microcystic variant). Urothelial carcinomas with abundant extracellular mucin extravasation have thus far not been reported.
Design: This study describes the clinicopathological characteristics of 13 cases and term this variant urothelial carcinoma with mucinous features. Thirteen cases of urothelial carcinoma with mucinous features were prospectively collected over 9 years. Cases with any areas of distinct adenocarcinoma component or micropapillary features were excluded from this study.
Results: The mean age of the patients was 64 years (range 45-84). Nine of the 13 were male. All cases involved the bladder with one of the cases involving a bladder diverticulum. Treatment included TURB only in 6 patients, TURB with subsequent intravesical BCG treatment in 4 patients, radical cystectomy only in 2 patients, and neo-adjuvant chemotherapy followed by cystectomy in 1 patient. All cases with extracellular mucin were invasive urothelial carcinomas. The two most common patterns of cancer with extracellular mucin were small or medium sized nests seen in 10 cases followed by filiform cancer seen in 4 cases. Other patterns of invasive cancer associated with extracellular mucin were cords, cribriform, pseudoglandular, and individual cells. The amount of invasive urothelial carcinoma with mucinous features compared to conventional invasive urothelial carcinoma in the samples ranged from 5 to 95% (mean 50%). An unusual finding was the presence of invasive low grade urothelial carcinoma associated with extracellular mucin in 5 cases, 4 of which had an overlying low grade papillary urothelial carcinoma component. All cases evaluated were uniformly positive for CK7 and negative for CDX2. Five cases were also positive for CK20, three were positive for MUC5 in the mucinous areas and 2 were positive for MUC2 in the mucinous areas. Two of the MUC5 positive cases were also focally positive for polyclonal CEA. Histochemical stains for alcian blue with and without hyaluronidase, PAS and mucicarmine showed positivity in both intra and extracellular compartments in all cases in the areas of mucinous differentiation.
Conclusions: The current study describes a novel variant of urothelial carcinoma which may be confused with either adenocarcinoma and micropapillary urothelial carcinoma, which can have therapeutic and prognostic implications.
Category: Genitourinary (including renal tumors)

Wednesday, March 11, 2009 9:30 AM

Poster Session V # 106, Wednesday Morning