Differentiating Nonfunctional Paraganglioma of the Bladder from Urothelial Carcinoma of the Bladder: Pitfalls and Breakthroughs

BACKGROUND: Although both nonfunctional paraganglioma of the bladder (NPB) and urothelial carcinoma of the bladder (UCB) are subtypes of bladder tumors, they are entirely different entities with distinct tissue origins and anatomical locations. However, NPB is frequently misdiagnosed as UCB chiefly due to the similarities in their clinical characteristics and cystoscopic features. This study aimed to compare the differences in their clinical characteristics and cystoscopic features. PATIENTS AND METHODS: Between April 2007 and September 2017, 14 patients with NPB (NPB group) were retrieved from 2 centers, and 42 patients with new-onset UCB (UCB group) were randomly retrieved. Demographic, symptomatic, imaging, and cystoscopic data of patients in both groups were collected and compared. RESULTS: NPB group comprised 7 males and 7 females, with a mean age of 43.1 ± 13.6 years. Compared with the UCB group, patients in the NPB group were significantly younger (p < 0.001), less likely to be male (p < 0.05), and to present with hematuria (p < 0.01). However, no significant difference in maximum tumor diameter was observed between the 2 groups (p=0.609). Compared with the UCB group, cystoscopically, patients in the NPB group were significantly more likely to present with hypervascularization but less likely to present with hemorrhage, necrosis, calcification, pedunculation, and multilesion (p < 0.05). No patients with NPB were clinically diagnosed correctly before cystoscopy. Of the 5 patients who underwent both cystoscopy and biopsy, 4 were diagnosed with NPB, while 1 remained undiagnosed. Of the remaining 9 patients who underwent cystoscopy only, 5 were diagnosed with nonepithelial tumor, and 4 were misdiagnosed with UCB. CONCLUSIONS: Age, sex, and hematuria may provide clues to differentiating NPB from UCB. Differences in cystoscopic features between NPB and UCB are of high diagnostic value. Cystoscopic biopsy should be considered in the preoperative diagnosis of NPB.