[776] Primary Carcinoid Tumors of the Urinary Bladder and Prostatic Urethra: A Clinicopathologic Study of 7 Cases.

Ying-Bei Chen, Jonathan I Epstein. The Johns Hopkins Hospital, Baltimore, MD

Background: Only 8 histologically well-documented cases of pure primary carcinoid tumors of the bladder and 1 of the urethra have been reported in the literature. Although they have been considered as potentially malignant, some prior reports were associated with carcinoma that might have altered the outcome.
Design: We describe 7 additional primary pure carcinoid tumors arising in the bladder (5 cases) or prostatic urethra (2 cases).
Results: Patients (5 males, 2 females), mean age 52 (35-60), presented with hematuria (n=5/7), obstruction (n=2/7) or for concurrent genitourinary diseases (n=1/7). The 5 bladder cases were located within or near the trigone and bladder neck. 6 cases shared gross and microscopic findings. Cystoscopy revealed small smooth-surfaced or polypoid nodules. Microscopically, these 6 tumors were subepithelial and confined within lamina propria, associated with adjacent cystitis cystica et glandularis. Tumors were composed of uniform cuboidal or columnar cells with finely stippled chromatin and inconspicuous nucleoli with a prominent pseudoglandular pattern composed of acinar and cribriform structures. Cells had moderate to abundant cytoplasm and basally located Paneth cell-like eosinophilic granules. Although occasional atypical cells with prominent nucleoli could be seen, mitotic activity was absent or rare and cases lacked necrosis. The 7th case was estimated to be at least 3 to 4 cm. In contrast to the other 6 cases, the predominant histologic patterns of this tumor consisted of tightly packed anastomosing trabeculae and large nests with a pseudoglandular pattern, while deeper areas demonstrated cords, small nests or individual cells in dense fibrotic stroma. Eosinophilic cytoplasmic granules were not identified. Despite involvement of the muscularis propria, the lesion was cytologically bland, lacked necrosis, and had only 1 mitosis/10 HPF. Neuroendocrine differentiation was confirmed by immunohistochemistry in all 7 cases. 6 of 7 tumors were completely excised by biopsies. There was no evidence of disease recurrence or progression in all 6 patients who had complete excision, including 3 patients who had clinical follow-up for more than 4 years.
Conclusions: Primary pure bladder/urethral carcinoids have distinct pathologic characteristics, with their prominent pseudoglandular features leading to difficulty in their diagnosis. Bladder/urethral carcinoids have a very favorable clinical outcome, and should be distinguished from mixed carcinoid tumors or urothelial carcinomas with neuroendocrine differentiation that display focal carcinoid-like histologic features.
Category: Genitourinary (including renal tumors)

Tuesday, March 1, 2011 9:30 AM

Poster Session III # 192, Tuesday Morning


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