Clinical significance of functional and anatomical classifications in paraganglioma of the urinary bladder.

OBJECTIVES: Paragangliomas of the urinary bladder (PUBs) are challenging catecholamine-producing neuroendocrine tumors. We aimed to facilitate their diagnosis and treatment by functional and anatomical classifications.

MATERIALS AND METHODS: Between April 2007 and September 2017, 31 cases from 2 centers were retrieved, in which the patients were pathologically diagnosed with PUB. Besides classifying them into functional and nonfunctional PUBs, functional PUBs were further subclassified into typical functional PUB (with typical symptoms and elevated catecholamines/metabolites levels) and atypical functional PUB. Anatomically, they were classified into submucosal, intramural, and subserosal PUBs.

RESULTS: Functionally, these cases comprised 17 (54.8%) functional and 14 (45.2%) nonfunctional PUBs. Functional PUBs had significantly larger diameters than nonfunctional PUBs (P < 0.01). Of the 17 functional PUB cases, 8 were further subclassified into typical functional PUB, of which 4 were diagnosed without cystoscopy. Anatomically, these cases comprised 14 (45.2%) submucosal, 13 (41.9%) intramural, and 4 (12.9%) subserosal PUBs. Intramural and subserosal PUBs had significantly larger diameters and were more likely to be functional than submucosal PUBs (P < 0.05). Cystoscopy failed to detect the tumor in all patients with subserosal PUB. Besides all patients with intramural or subserosal PUB, 1 patient with submucosal PUB underwent partial cystectomy. The remaining 13 patients with submucosal PUB underwent transurethral resection of bladder tumor, 5 of whom required extra surgical intervention.

CONCLUSIONS: By functional classification, omitting cystoscopy is feasible in the diagnosis of typical functional PUBs. By anatomical classification, intramural, and subserosal PUBs tend to be large and functional. Moreover, negative cystoscopic findings are not sufficient to exclude subserosal PUBs. Finally, not all submucosal PUBs are amenable to transurethral resection of bladder tumor.