Endocrine Abstracts

JOINT85

Background: Phaeochromocytomas are catecholamine-secreting tumours originating from chromaffin cells in the adrenal medulla and can be symptomatic or asymptomatic. They may arise sporadically or in the context of hereditary syndromes such as MEN2, VHL, and hereditary paraganglioma-phaeochromocytoma (PGL-PCC) syndrome. Germline MAX gene mutations are a rare but known cause of hereditary PGL-PCC syndrome, manifesting as phaeochromocytomas/paragangliomas in affected patients.

Methods: This is a case report of a young patient with a pathogenic MAX gene variant who developed metachronous bilateral phaeochromocytomas.

Case Presentation: A 31-year-old lady with known hypertension presented with significant weight loss over one year, associated with increasing lethargy and episodes of diaphoresis. Her urine catecholamines and metanephrines were significantly elevated (adrenaline 2x above ULN and noradrenaline 37 × above ULN), and magnetic resonance imaging of her abdomen revealed a large 9cm left suprarenal mass. Right adrenal gland was normal. She was clinically diagnosed with a left phaeochromocytoma and underwent left adrenalectomy. Her young age at presentation prompted suspicion of hereditary syndromes – further genetic testing identified a pathogenic MAX gene variant associated with autosomal dominant hereditary PGL-PCC syndrome. Predictive testing was offered to at-risk family members. Subsequently, the patient was monitored for recurrence with annual urine catecholamine/metanephrine levels, and a full body MRI was performed every two to three years for the detection of paragangliomas. Despite the patient being asymptomatic, post-operative surveillance detected a right adrenal nodule two years later, followed by steadily rising urine catecholamine/metanephrine levels five years later. She was initially reluctant for surgery as she was asymptomatic but eventually opted for right adrenalectomy nine years later. Post-operatively, the patient was prescribed lifelong glucocorticoid and mineralocorticoid replacement therapy. She is currently well and remains under close follow-up and surveillance.

Conclusion: This case demonstrates the importance of genetic testing in young patients diagnosed with phaeochromocytoma. Predictive testing should be offered to at-risk family members. Close surveillance with biochemical screening and imaging is paramount to detect recurrence and/or new disease, even in the absence of symptoms. In patients with pathogenic MAX gene variants, a full body MRI extending from the base of skull to the coccyx is recommended.