An exception to the rule: ectopic ACTH production from functional neuroendocrine tissue in an ovarian dermoid cyst

Ectopic ACTH production accounts for 15% of Cushing's syndrome presentations and is characterized by the presence of an excess of ACTH precursors. However in the case presented here ectopic ACTH production was from functional pituitary tissue within an ovarian dermoid cyst. Endocrine investigations showed that the problem behaved more like pituitary-dependent Cushing's disease and this is discussed. Furthermore, this case is one of familial dermoid cysts, another unusual phenomenon.