Fig. 23.19 Cushing's syndrome: ectopic ACTH production by a carcinoid tumour of the lung. Cushing's syndrome sometimes results from ectopic ACTH production by tumours, particularly of the lung, thymus or pancreas. Such tumours may be very difficult to locate. Although a few may be detected by conventional radiographic techniques, others require CT scanning or venous sampling for their identification, and some are never found. The PA chest film (a) shows a small mass in the left lower zone. There is some generalised loss of bone density and the patient appears fat. On the lateral view (b) the mass is shown to lie in the lingular segment of the left upper lobe. The patient had Cushing's syndrome secondary to ectopic ACTH production by a benign bronchial carcinoid tumour of the lung.
