Paraganglioma of the urinary bladder with a novel variant of SDHB mutation.

Urinary bladder paragangliomas (UBPGLs) are rare neuroendocrine tumours, comprising <0.05% of bladder neoplasms. We report a case of a male in his early 30s presenting with persistent lower abdominal discomfort. Imaging showed a hypervascular extraluminal mass on the posteroinferior aspect of the urinary bladder wall with suspicion of a soft tissue tumour likely paraganglioma (PGL). His biochemical markers were within normal limits. The patient underwent open partial cystectomy without complications. Histopathology confirmed PGL with classic zellballen architecture and immunohistochemistry was positive for synaptophysin and chromogranin A. Hence, diagnosis of non-functional UBPGL was confirmed. Genetic testing revealed a pathogenic SDHB mutation (c.550dup) associated with increased metastatic risk. Postoperative recovery was uneventful and follow-up 68Ga-DOTATOC PET-CT showed no evidence of recurrence or metastasis. This case highlights the importance of integrating imaging, histopathology and genetic analysis for management of non-functional UBPGLs and long-term surveillance of this rare entity.