Evaluation of surgically treated Nelson's syndrome.

In 17 primary transnasal operations on Nelson tumours long-term results are assessed measuring ACTH plasma levels and performing regular neuroradiological controls. In small intrasellar adenomas only one recurrent ACTH elevation near to pretreatment levels without symptoms from tumour growth was observed after 10 years. ACTH normalization was rarely achieved in large tumours, but only in one patient was a relapse visible in CT scan after three years. Thus selective tumour removal seems to be advisable at an early stage when sellar enlargement occurs. Interpretation of ACTH plasma levels has to include completeness of adrenalectomy, cystic tumour necrosis, and corticoid replacement which reduces ACTH levels. Elevation of ACTH plasma levels over 5,000 pg/ml has been regularly accompanied by extrasellar tumour extension. In large adenomas with definitely elevated ACTH levels, additional radiation therapy should be considered.