Human adenohypophysis in Nelson syndrome. Ultrastructural and clinical study.

The manifestations that comprise the disease known as Nelson syndrome are pituitary hyperplasia and cutaneous hyperpigmentation, which sometimes follow bilateral adrenalectomy, in patients with hypercortisolism. We present a comprehensive endocrinologic, structural study of a patient in whom the evidence obtained supports the hypotheses that: (a) the primary disorder in this form of hypercortisolism is probably hypothalamic; (b) the hyperplasia of the adenohypophysis, following adrenalectomy, is closely associated with lowered plasma cortisol levels; and (c) the cillular hyperplasia in the adenohypophysis involves primarily the corticotroph, a cell believed to be associated with the secretion of adrenocorticotrophic hormone and melanocyte-stimulating hormone.