[Metastatic pulmonary carcinoma, revealed by Cushing syndrome, initially considered to have a pituitary origin....

It is often difficult to differentiate between Cushing's syndrome and ectopic ACTH hypersecretion which, in rare cases, may result from a carcinoid tumour. Several years may be required before development of patent Cushing's syndrome. We report the 25-year clinical course in a patient with a pulmonary carcinoid tumour. Initially, the hormone results led to the diagnosis of Cushing's syndrome and the patient was treated accordingly. Bilateral adrenectomy was performed in 1969 followed by radiotherapy of the pituitary gland in 1975 for suspected Nelson's syndrome. Actually, the carcinoid tumour, located retrocardially, had gone unnoticed until 1989. Diagnosis was suspected during a hospitalization in our unit and the patient underwent tumour exeresis and left inferior lobectomy. Despite tumour removal and demonstration of tumoural ACTH secretion, the levels of ACTH and beta-lipotrope hormone remained high suggesting lymph node and/or pulmonary metastasis. This observation emphasizes the long clinical course of carcinoid tumours despite their malignancy and the unusual response to the dexamethasone test.