A 42-year-old man with dermatomyositis presented with right-upper-quadrant dull pain and normal blood pressure for 10 days. Abdominal ultrasonography, abdominal computed tomography, and angiography revealed a retroperitoneal tumor with direct invasion to the liver and the diaphragm. The diagnosis of nonfunctioning malignant pheochromocytoma was made on the basis of clinical evidence. The tumor was removed en bloc with part of the diaphragm, the right lobe of the liver, the right adrenal gland, and the right kidney. Pathologic examination with immunohistochemical staining revealed a malignant pheochromocytoma growing exophytically from the right adrenal gland and invading the right lobe of the liver and the diaphragm. The postoperative course has been uneventful and no recurrence has been noted over a 6-month follow-up period.