Metastatic small cell carcinoma of the lung presenting as pituitary apoplexy and Cushing's syndrome.

We describe a woman with metastatic small cell carcinoma of the lung who presented with pituitary apoplexy and hyperprolactinemia. Within seventeen months she developed florid Cushing's syndrome with anasarca, hyperpigmentation, hypertension with marked hypercortisolemia (not suppressible with 8 mg dexamethasone), elevated serum ACTH, hypokalemic metabolic alkalosis, and multiple hepatic metastases. This picture suggested the presence of ectopic ACTH syndrome. She died 26 months after the episode of pituitary apoplexy. Primary small cell carcinoma of the lung was diagnosed post-mortem. Metastases were present in the left lung, regional lymph nodes, heart, liver, bone marrow, sphenoid bone, anterior pituitary and pituitary capsule. Posterior pituitary was normal. There was no evidence of pituitary hyperplasia, of adenoma or of primary pituitary carcinoma. The results suggest the presence of a primary ACTH-producing small cell carcinoma of the lung that metastasized to the parasellar sphenoid bone and then extended to the anterior pituitary and dura to mimic a primary intrasellar cause of pituitary apoplexy and Cushing's syndrome. The case demonstrates how difficult it may be to diagnose the etiology of Cushing's syndrome and it emphasizes a unique variation in the presentation of small cell carcinoma of the lung.