The great mimicker of the bladder: paraganglioma masquerading as urothelial carcinoma

Abstract

Urinary bladder paraganglioma is an exceptionally rare extra-adrenal neuroendocrine tumor arising from chromaffin cells, accounting for less than 0.05% of all bladder tumors. Due to nonspecific clinical presentation and overlapping radiological features, it is frequently misdiagnosed as urothelial carcinoma. Definitive diagnosis relies on histopathology with immunohistochemistry. A 63-year-old female presented with increased urinary frequency for eight months without hematuria or catecholamine-related symptoms. Imaging revealed a polypoidal lesion in the posterior bladder wall with calcification, suggestive of malignancy. The patient underwent transurethral resection of bladder tumor. Histopathology showed tumor cells arranged in nests with characteristic “salt and pepper” chromatin, raising suspicion of paraganglioma. Immunohistochemistry demonstrated positivity for chromogranin and synaptophysin, with negative epithelial markers and a low Ki-67 index, confirming the diagnosis. The postoperative course was uneventful. Bladder paragangliomas are rare and often indistinguishable from urothelial carcinoma clinically and radiologically. Non-functional tumors further complicate diagnosis. Histopathological overlap necessitates immunohistochemical confirmation. Transurethral resection may be both diagnostic and therapeutic in localized cases. Bladder paraganglioma should be considered in the differential diagnosis of bladder tumors. Early recognition and immunohistochemistry are essential for accurate diagnosis. Complete surgical excision with long-term follow-up is recommended.