[Cushing's syndrome caused by paraneoplastic ACTH secretion 11 years after occurence of a medullary thyroid carcinoma].

HISTORY AND ADMISSION
FINDINGS: A 47-year-old man, with known and treated hypertension for 2 years, was admitted because of recent marked weight gain. Eleven years before a medullary thyroid carcinoma had necessitated removal of his thyroid and parathyroids. He was not receiving levothyroxine, calcium and vitamin D. Physical examination revealed florid Cushing's syndrome with a "buffalo hump", plethora, truncal obesity and red striae. Both his mother and a maternal male cousin were reported to have had a medullary thyroid carcinoma. INVESTIGATIONS: Plasma ACTH was 80 pg/ml (normal 10-70 pg/ml), urinary cortisol 764 microgram/24 h (normal 20-100 microgram/24 h). ACTH rose to 93.1 pg/ml after dexamethasone, with little suppression of serum cortisol (reduced from 34.4 to 22.1 microgram/dl; normal 7-25 microgram/dl. Magnetic resonance imaging did not detected an abnormal hypophysis. Petrosal sinus catheterization revealed hypophyseal suppression of ACTH, without evidence of focal peripheral ACTH production. Calcitonin was 24 000 pg/ml (normal < 8.8 pg/ml). Computed tomography showed multiple round lesions in the liver (histology: metastasis of a C-cell carcinoma). Genetic test showed a multiple endocrine neoplasm type IIa. DIAGNOSIS, TREATMENT AND COURSE: The findings indicated Cushing's syndrome, most likely due to paraneoplastic ACTH secretion from a metastasis of the C-cell carcinoma. In the absence of a site of paraneoplastic ACTH secretion, bilateral adrenalectomy was performed. The plethora and striae regressed postoperatively and it was possible to reduce markedly the antihypertensive medication.
CONCLUSION: An ectopic site of ACTH should be included in the differential diagnosis of Cushing's syndrome. This is the first reported case of a medullary thyroid carcinoma and ectopic ACTH production in which the paraneoplastic ACTH secretion had been delayed for 11 years.