Pitfalls of Functional Tests for the Establishment of the Etiology of Cushing's Syndrome in Childhood and Adolescence

The clinical course and results of steroid measurements before and during different tests of pituitary adrenal function are presented in 3 boys and 1 adolescent girl with Cushing's syndrome. Two of the boys had bilateral adrenal hyperplasia even though their cortisol production rates and pituitary adrenal function tests were typical of adrenal tumors. One of them developed central nervous system hemorrhages and died. At autopsy a basophilic adenoma of the pituitary was found. The third boy had a malignant thymoma which was probably secreting an ACTH-like substance. His cortisol production rate was also very large and it could not be suppressed with dexamethasone. The adolescent girl had a moderate hypercorticism. Functional tests were typical of Cushing's syndrome due to bilateral adrenal hyperplasia. Surprisingly, she improved markedly without any specific treatment.