A 45-Year-Old Female with Hypokalemic Rhabdomyolysis due to VIP-Producing Composite Pheochromocytoma

The watery diarrhea, hypokalemia and achlorhydria (WHDA) syndrome due to vasoactive intestinal polypeptide (VIP)-producing extra-pancreatic tumors is rare. We report on a 45-year-old woman who suffered from persistent secretory diarrhea for six years and who was admitted to hospital with complaints of muscular weakness and myalgia. Biochemical testing revealed pronounced rhabdomyolysis due to severe hypokalemia. Gastrointestinal evaluation of long-standing diarrhea including endoscopy of the upper and lower gastrointestinal tract and the small intestine did not show any pathologies. An abdominal computed tomography scan revealed a mass of 4 x 5 cm in the left adrenal gland demonstrating a strong uptake in the I-123-labelled metaiodoben-zylguanidine scintigraphy. Plasma levels of chromogranin A, calcitonin, parathormone, basal renin and most prominently VIP were increased in line with a increased 24 hour urinary secretion of noradrenaline, dopamine, normetanephrine and vanillymandelic acid. A WDHA (watery diarrhea, hypokalaemia, achlorhydria) syndrome with hypokalemic rhabdomyolysis due to a VIP-producing adrenal tumor was diagnosed that was removed surgically. The histological evaluation demonstrated a composite pheochromocytoma. Diarrhea stopped immediately after surgery together with a normalization of laboratory parameters. In conclusion, this case report focuses on the rare clinical presentation of secretory diarrhea and electrolyte disturbances in combination with hypokalemic rhabdomyolysis which was caused by a VIP-producing composite pheochromocytoma.