Composite pheochromocytoma–ganglioneuroma secreting vasoactive intestinal peptide
Abstract
Summary An 80-year-old female patient presented with a 10-year history of progressively worsening diarrhea and chronic hyponatremia. An abdominal computed tomography (CT) revealed a 6.8-centimeter right adrenal mass. A Ga-68 DOTATATE positron emission tomography (PET)/CT scan subsequently demonstrated a significant expression of somatostatin receptors on the tumoral shell (maximal SUV of 14.4), associated with a hypometabolic central portion. Endocrine investigation indicated elevated levels of both urinary and plasmatic normetanephrines. Given the watery diarrhea, VIP levels were measured, which were markedly elevated. Surgical resection confirmed a composite pheochromocytoma–ganglioneuroma with VIP immunoreactivity in both tumor components. In the postoperative period, the plasma levels of VIP and normetanephrines returned to normal with resolution of diarrhea, hyponatremia, and hypertension. This case illustrates a rare instance of composite pheochromocytoma–ganglioneuroma with co-secretion of catecholamines and VIP, with evidence of VIP production in both tumor components. The finding of VIP secretion in the pheochromocytoma and the ganglioneuroma suggests that both tumors might originate from the same cell of neural crest origin. Learning points Pheochromocytomas are frequently associated with excessive catecholamine production and can rarely co-secrete VIP, leading to secretory diarrhea and electrolyte disturbances, such as hypokalemia and hyponatremia, while pheochromocytomas usually lead to constipation. Chronic watery diarrhea refractory to standard treatments should prompt evaluation for rare neuroendocrine tumors, such as VIP-secreting pheochromocytomas or composite adrenal tumors, especially when imaging reveals adrenal masses. Surgical removal of composite pheochromocytoma–ganglioneuroma with VIP co-secretion can lead to complete resolution of diarrhea, normalization of electrolytes, and stabilization of blood pressure, underscoring surgery as definitive therapy.