SAT-LB306 A Case of Synchronous Non-Functioning Paraganglioma of the Urinary Bladder and Prostate Cancer

Introduction The bladder is an uncommon site for a paraganglioma, with only <1% of all paragangliomas occurring in the bladder. Management of non-functioning bladder paraganglioma is uncharted due to its rarity, and there is even less data for cases with synchronous malignancy. We found two case reports of synchronous paraganglioma and prostate cancer, only one in the bladder. Here we report a second case and discuss management. Clinical Case A 72-year-old man with high risk prostate cancer, Grade group 5 on biopsy, was found to have a 1.2 x 1.6 cm bladder wall mass on staging CT scan. The transmural mass was only partially resectable via transurethral approach. Pathology unexpectedly revealed paraganglioma, confirmed by immunohistochemical stains for Synaptophysin, Chromogranin, and CD56. The patient had longstanding hypertension controlled on losartan and denied any symptoms of catecholamine excess. He had no family history of paraganglioma, pheochromocytoma, or related neoplastic syndrome. Plasma free metanephrine and normetanephrine levels were 57pg/mL (normal 57pg/mL) and 157pg/mL (normal 148pg/mL), respectively. Urinary studies were not performed due to stage 4 chronic kidney disease. Staging CT scan and bone scan did not show any other lesions. Even in cases of known distant metastases of paraganglioma, surgical resection of all tissue is recommended if possible. Thus, he underwent radical prostatectomy, bilateral pelvic lymphadenectomy and partial cystectomy. Prostate cancer was downgraded to Grade group 2, pT3aN0Mo and complete excision of the paraganglioma was confirmed. Evaluating for metastases and follow up are challenging in all paraganglioma cases, but especially non-functioning paragangliomas. Bladder paragangliomas carry a 10-15% risk of malignancy, but no separate data is reported for non-functioning ones. Histology scoring systems that are somewhat predictive in pheochromocytoma are less helpful in paragangliomas. Imaging is also challenging. CT, MRI, and a variety of functional imaging modalities have sensitivities for paraganglioma metastases in the range of 50 – 94% depending on location, functionality, and presence of germline mutation. For now, we recommend non-contrast CT with 18F-fluoro-2-deoxy-2-D-gluocse (FDG) PET. Though guidelines recommend annual biochemical surveillance, the usefulness in non-functioning paraganglioma is questionable. Genetic testing is recommended for all patients with paraganglioma. Succinate dehydrogenase B (SDHB) is most important given the propensity for metastases. Thus, we recommended the SDHx germline mutation package. Clinical Lesson This case is the second reported synchronous bladder paraganglioma and prostate cancer. It highlights the challenge, lack of data, and need for advancement in our knowledge for the best management of incidental, non-functioning, extra-adrenal paragangliomas.