Two Unusual Variants of Nelson's Syndrome*

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Abstract
Two unusual variants of Nelson's syndrome are described. The first patient, a 36-yr-old female, developed concomitantly clinical and laboratory evidence of Cushing's and Nelson's syndromes some 3 yr after an inadvertently incomplete bilateral adrenalectomy for adrenal hyperplasia. The patient also was documented to have schizophrenia predating the onset of clinical Cushing's disease. Pituitary microadenomectomy resulted in a pronounced fall in ACTH levels (400–600 pg/ml) to 100 pg/ml postoperatively, with improvement both of Cushing's and Nelson's syndrome. One year after operation, ACTH was relatively fixed at 150 pg/ml and was not suppressible with dexamethasone. Although microadenomectomy resulted in improvement of paranoia and auditory hallucination, the patient still appears to be schizophrenic. This appears to be the first reported instance of the coexistence of Cushing's syndrome and Nelson's syndrome in a patient not under treatment with steroids. The second patient, a 23-yr-old female, developed ocularparesis attributed to an ectopic chromophobe adenoma, which was incompletely removed at age 18 yr. This mass appeared to be parasellar in location and had no visible connection to the pituitary proper. Immunocytochemical studies of the ectopic adenoma showed clusters of cells with a high intracellular ACTH concentration. The patient subsequently developed Cushing's disease at age 19 yr. Bilateral adrenalectomy was performed.Laboratory and clinical evidence of Nelson's syndrome developed some 3 months later. High ACTH values (8200 pg/ml) were only partially suppressed (to 1500 pg/ml) with 8 mg dexamethasone/ day. A remnant of the adenoma was believed to be responsible for elevated ACTH. This patient appears to be the first example of Nelson's syndrome arising from an ectopic pituitary adenoma.

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