Pituitary pro-opiomelanocortin-cell carcinoma occurring in conjunction with a glioblastoma in a patient with Cushing's disease and subsequent Nelson's syndrome.

Pituitary carcinoma is defined as a malignant pituitary tumour associated with blood- or lymph-borne metastases. Cushing's disease is frequently present in patients with this condition. After adrenalectomy for Cushing's disease, a 37-year-old man developed Nelson's syndrome resulting from a pituitary carcinoma with metastases to the spinal cord, cauda equina, heart, liver, and pancreas. The primary tumour and its metastases showed immunocytochemical staining for ACTH, beta-lipotrophin, and variably for beta-endorphin and alpha-melanocyte stimulating hormone (alpha-MSH). A coincidental glioblastoma was also present. Nine cases of Cushing's disease associated with pituitary carcinoma, including the present patient, are documented in the literature. The case reported is only the second in which immunohistochemical staining of the primary pituitary tumour and its metastases was performed, and the first in which ACTH-related peptides, in addition to ACTH itself, were demonstrated in the carcinoma cells.