The authors report a case of a large pseudocystic pheochromocytoma, which initially was operated on and histologically diagnosed as a pancreatic pseudocyst. After recurrence, a multilocular cystic tumor was found both by ultrasonography and CT. ERCP demonstrated a cut-off of the pancreatic duct. Re-operation revealed a cystic adrenal tumor anastomosed to the stomach. The operation was complicated by a hypertensive crisis and a subsequent subendocardial infarction. In the preoperative period the patient had continuous diarrhea and pneumatosis cystoides intestinalis was demonstrated by double contrast barium enema. The pneumatosis disappeared within three months but a recurrent tumor appeared. The importance of CT in the preoperative work-up of upper abdominal lesions is emphasized, as atypical cystic masses may cause differential diagnostic problems in surgery or even in localized biopsies, while CT would give a better overall view of the tumor.