Surgical Remission of Diabetes in a Patient With Mutation of RET Proto-Oncogene

Objective: In pheochromocytomas, accelerated catecholamine production can cause secondary diabetes. The gene responsible for multiple endocrine neoplasia type 2 (MEN2)-related pheochromocytomas is the RET proto-oncogene. The objective of this report is to describe a unique case of surgical remission of misdiagnosed type 2 diabetes mellitus (T2DM) in a woman with bilateral pheochromocytoma and RET proto-oncogene mutation. Methods: Clinical examination, urinary metanephrine level, triple-phase abdominal computed tomography (CT) with adrenal protocol, positron emission tomography with ¹⁸F-fluorodeoxyglucose integrated with CT, surgical pathology, and genetic testing were performed. Results: A 46-year-old woman with a 5-year history of apparent T2DM complicated by neuropathy, without a contributory family history, presented with occasional headaches, weight loss, and abdominal pain. A 24-hour urinary metanephrine of 5 mg (reference range, 0.05-1 mg) was found. Abdominal CT showed bilateral adrenal masses with <60% washout. Positron emission tomography with ¹⁸F-fluorodeoxyglucose integrated with CT showed a left solid-cystic lesion with low metabolic activity and a right nodular lesion with a higher metabolic activity, which was conclusive of bilateral pheochromocytoma. The remission of diabetes was achieved 1 year after a bilateral adrenalectomy. In addition, a multinodular goiter was found, and a fine-needle aspiration biopsy confirmed that it was a medullary thyroid carcinoma. A heterozygous pathogenic variant of the RET proto-oncogene was found and MEN2A was confirmed. Conclusion: This is the first report of a patient with a RET proto-oncogene mutation experiencing remission of diabetes after surgical resection of bilateral pheochromocytomas. Timely recognition and treatment of the underlying condition are important to potentially achieve diabetes remission and prevent its long-term complications.