A 61-year-old woman who had a nonfunctioning pituitary tumor removed was later found to have a pituitary carcinoma with metastasis to the liver that produced adrenocorticotropic hormone (ACTH), causing Cushing's disease. Despite the second removal of the pituitary tumor, Cushing's disease persisted. Endocrinologic examination demonstrated marked elevation of plasma ACTH, β-endorphin, and serum cortisol concentrations, which were not suppressed by low- or high-dose dexamethasone administration. A computed tomographic scan of the abdomen revealed a solitary hypodense area in the liver consistent with a metastatic lesion. Immediately after resection of the liver tumor, plasma ACTH concentrations fell to normal range. Such a decline in ACTH secretion was not observed even after the pituitary tumor was removed. Histologic characteristics of both the pituitary and liver tumors were similar. The immunohistochemical study using anti-ACTH antibody showed similar ACTH-positive cells in the pituitary and liver tumors. Based on these findings, the patient was diagnosed as having liver metastasis of ACTH-secreting pituitary carcinoma. This is the first case report in which a metastatic liver tumor of a pituitary carcinoma caused ACTH.
2002 The Japan Endocrine Society