Nelson's syndrome is a pituitary adenoma occurring as a result of undergoing a bilateral adrenalectomy, an operation for Cushing's Disease.

Removal of both adrenal glands eliminates production of cortisol, and the lack of cortisol's negative feedback can allow any preexisting pituitary adenoma to grow unchecked. Continued growth can cause mass effects due to physical compression of brain tissue, along with increased production of adrenocorticotrophic hormone (ACTH) and melanocyte stimulating hormone (MSH).

The common signs and symptoms include muscle weakness and skin hyperpigmentation due to excess MSH. Nelson's syndrome is rare because bilateral adrenalectomy is now only used in extreme circumstances.

Eponymous diseases | Diseases