Cushing's disease due to an unusually large adenoma of the pituitary gland in infancy

We report an 18-month-old girl with Cushing's disease caused by a large adenoma of the pituitary gland. Tumour size and extension were determined by X-ray, CT-scan and angiographic studies. The endocrinological findings were typical for this disease: elevated plasma levels of ACTH, cortisol, 17-Hydroxyprogesterone (17-OHP) and testosterone, elevated urinary excretion of 17-Ketosteroids (17-KS) and 17-Hydroxycorticoids (17-OHCS). Dexamethasone failed to suppress ACTH and cortisol plasma levels. TRH induced only a minimal TSH increase. Following LH-RH injection gonadotropin levels rose to pubertal values. The hGH response to insulin-induced hypoglycaemia was subnormal. After resection of the tumour the infant died because of non-treatable arrhythmia. Histological findings showed a non-differentiated adenoma with extension into the subarachnoid space and into nerve tissues. In vitro lysine-vasopressin (LVP) and arginine-vasopressin (AVP) exhibited only weak stimulatory effects on the ACTH secretion of the tumour cells.