Endocrine Abstracts

A 32 year-old man was referred with complaints of weight gain, sweating and a rash. Examination revealed a moon face, hypertension, centripetal obesity, a dorsal fat pad, and violaceous abdominal striae. A diagnosis of Cushing's syndrome was suspected.

Urine free cortisol was elevated (3674 nmol/24hrs) with an unsuppressed ACTH level (39ng/l). Serum and urine cortisol failed to suppress with low and high dose dexamethasone. Corticotrophin Releasing Factor (CRF) administration failed to increase ACTH levels. On inferior petrosal sinus sampling the ratio of central to peripheral blood ACTH levels was < 1 pre- and post-CRF administration.

Chest-X-ray was normal. CT Thorax demonstrated a 5 mm nodule in the right lung parenchyma. Somatostatin receptor scintigraphy showed no abnormal uptake. This lesion was felt to be too small to permit fine needle aspiration. The patient was commenced on ketoconazole with initial response. Follow-up CT scanning at 6 and 12 months revealed no change in appearance of the nodule. Cortisol levels were rising despite treatment. Attempted percutaneous needle aspiration of the nodule was unsuccessful. Cortisol and ACTH levels dropped after a test dose of octreotide and long-acting octreotide was commenced. Urine free cortisol normalised on treatment. .

The patient underwent open removal of the lung nodule. Histology confirmed a bronchial carcinoid with positive ACTH immunostaining. Cortisol levels have remained normal post-operatively off somatostatin treatment.

We report a case of ectopic ACTH secretion where the only radiologically detected possible source was a tiny, benign appearing lung lesion. Despite negative receptor scintigraphy, ACTH secretion was suppressed by somatostatin. Following careful consideration, the lesion was resected with apparent cure of the patient's disease and an ACTH-secreting bronchial carcinoid, a rare condition which accounts for <1% of cases of Cushing's Syndrome, was revealed. Thus, bilateral adrenalectomy, sometimes performed in this situation, was avoided.