[New aspects of the pathogenesis of acromegaly-somatoliberinomas].

According to modern knowledge, acromegaly can develop in at least three ways. A pituitary adenoma with growth hormone overproduction is the most frequent. Much rarer is ectopic growth hormone secretion by extra-hypophyseal tumors. A further possibility is the production of growth hormone releasing factor (GRF) by hypothalamic or ectopic tumors. This involves the secretion of a substance which selectively stimulates the GH producing cells of the pituitary. Special features of the clinical and morphological picture of this condition are described, based on the authors own observations. Two patients developed acromegaly: one had a retroperitoneal paraganglioma and the other a bronchial carcinoid. Ectopic GRF secretion could be confirmed radioimmunologically and immunohistologically in both cases. As a result of the on-going, tumor related GRF stimulation the patients developed nodular or diffuse GH-cell hyperplasia in the adenohypophysis. Since ectopic GH secretion does not cause hyperplasia of the adenohypophyseal cells, morphologic examination of the hypophysis can contribute to the differential diagnosis in such cases.