Presyncope in a Woman With Incidental Bladder Mass: A Case of De Novo SDHB Mutation Bladder Paraganglioma

Background: Paragangliomas (PGLs) are catecholamine secreting neuroendocrine tumors originating from extra-adrenal neural crest cells. Urinary bladder paragangliomas (UBPGLs) are extremely rare, accounting for only 0.06% of all bladder tumors. Sporadic UBPGLs associated with Succinate Dehydrogenase B (SDHB) mutation have a higher malignant potential versus patients with a positive family history due to a lack of screening. We present a case of sporadic UBPGL detected early due to follow-up of an incidental bladder mass. Clinical Case: A 31 year-old female presented to the ER with presyncope and lower abdominal pain while running. On arrival she was mildly hypertensive with BP 140/88 mmHg, HR was 98 beats/min, other vital signs were stable. Denied headaches, diaphoresis, or weight loss. No known personal or family history of any endocrine disorders or cancer. CT abdomen pelvis performed for the evaluation of her abdominal pain revealed a large fibroid along with an unexpected finding of a 3 cm enhancing lesion in the right bladder wall, suggestive of a PGL. 24 hr urine total catecholamines and plasma total metanephrines were elevated at 284 mcg (normal range 26-121 mcg/24h), and 386 pg/mL (normal <205 pg/ml) respectively, confirming the diagnosis of UBPGL. Chromogranin A was within the normal range. Metastasis was ruled out with metaiodobenzylguanidine (MIBG) whole-body scan and octreotide scan which showed isolated uptake in the bladder. Pan CT scan was negative for other SBHB mutation associated tumors such as RCC (14% incidence), GIST, and thyroid carcinoma. Genetic testing with PGLNest revealed a heterozygous SDHB mutation (5’-3’ UTR_5’-3’ UTR deletion). Her parents were found to be negative for the mutation. During follow up she developed episodic palpitations. She was treated with alpha followed by beta blocker and underwent successful resection of the tumor with partial cystectomy, and of the fibroid with myomectomy on the same day (TAH was avoided to minimize manipulation of the uterus hence decreasing the risk of intra-abdominal HTN crisis). She has been tumor-free in the three years of follow up post-surgery with imaging and biochemical surveillance. Conclusion: This case illustrates the importance of following up on incidental radiographic findings and adds to the limited literature on sporadic UBPGLs, an uncommon, yet potentially life-threatening tumor. The diagnosis of these tumors is especially challenging when patients present with non-specific symptoms. Fortunately, in our case, the imaging study clued us into the possibility of a PGL. SDHB mutation associated PGLs, in particular, are notorious for their late presentation with metastasis and associated tumors. Hence, timely detection with close follow-up of these patients will likely have an impact on their mortality.