Adrenocorticotropic hormone-producing pituitary carcinoma with intracranial metastases.

BACKGROUND: Pituitary carcinomas are rare and challenging clinical entities. Because of the paucity of cases, there is limited information in the literature on how best to diagnose and treat pituitary carcinomas.
METHODS: We review the literature and describe a woman who presented with an adrenocorticotropic hormone (ACTH)-secreting pituitary macroadenoma that later evolved into a carcinoma with intracranial metastases.
RESULTS: A 39-year-old woman presented at age 27 with classic findings of Cushing's syndrome and a pituitary macroadenoma. Her initial treatment was transsphenoidal surgery, during which we confirmed an ACTH-secreting pituitary neoplasm. For 5 years, she was asymptomatic before her first recurrence. During the next 6 years, she underwent four transsphenoidal surgeries and two craniotomies. After each surgery, there was some reduction in the size of the macroadenoma but the residual tumor mass would rapidly enlarge. Immunochemical staining was positive for ACTH, and a stain for Ki-67 antigen showed a high mitotic index. Eleven years after her initial presentation, magnetic resonance imaging revealed bilateral hippocampal and tempero-occipital masses. The patient's health continued to deteriorate, largely from complications of severe hypercortisolemia, and she died from sepsis. At postmortem, the hippocampus and tempero-occipital lobe masses proved to be a pituitary tumor with positive ACTH staining.
CONCLUSIONS: Pituitary carcinomas are rare, may present many years after diagnosis of a primary pituitary adenoma, and should be suspected in patients with persistent or recurrent disease. Reliable histopathologic ways to distinguish between carcinoma and adenoma are difficult because the features of hypercellularity, nuclear pleomorphism, and mitotic figures are not always helpful.