An incidentaloma is a tumor found incidentally without clinical symptoms or suspicion; the lesion may be adrenal, pituitary, or thyroidal. We report the case of an asymptomatic individual with preoperatively undiagnosed pheochromocytoma (size: 4.86 cm) that was revealed using elective nonadrenal surgical procedures. The patient demonstrated peri- and post-operative hypertensive crisis and tachycardia. Three days after the dramatic onset of symptoms, the patient expired due to pulmonary edema, multiple organ failure, and terminal sepsis, despite administration of extracorporeal membrane oxygenation-assisted cardiopulmonary resuscitation. A left medial kidney mass obtained at autopsy confirmed pheochromocytoma.