ACTH secreting pituitary adenoma in an infant of 18 months: Immunohistochemical, electron- microscopic, and in-vitro studies

Abstract

An 18-month old infant with Cushing's disease due to an ACTH producing pituitary tumor is presented. The case showed typical clinical and morphological sings of hypercortisolism. The infant died of pulmonary thromboembolism after transsphenoidal partial adenomectomy. The adrenals were diffusely hyperplastic. The pituitary adenoma was classified as an undifferentiated mucoid cell adenoma with sparse granulation by light microscopy. Immunoenzymatic studies demonstrated ACTH not only in granulated adenoma cells. Ultrastructurally the cells were only differentiated as typical ACTH cells or so-called follicular cells in small areas. Most of them were undifferentiated, showing pleomorphism of the relatively sparse organelles. In-vitro experiments using suspensions of adenoma cells showed a distinct enhancement of ACTH secretion after arginine-vasopressin and a further decrease ultrastructurally in the number of secretory granules. No effect of ACTH levels and no alterations of the ultrastructure were observed after cortisol. The case is representative of typical hypothalamic-hypophyseal Cushing's disease with an undifferentiated pituitary adenoma secreting ACTH in part autonomously. This constellation of Cushing's syndrome is extremely rare at the age of one year. Our case is the second one reported in the literature.