ECTOPIC ADRENOCORTICOTROPIN SYNDROME-ASSOCIATED WITH UNDIFFERENTIATEDCARCINOMA OF THE COLON SHOWING MULTIDIRECTIONAL NEUROENDOCRINE, EXOCRINE, AND SQUAMOUS DIFFERENTIATION

We report a rare case of ectopic ACTH syndrome associated with undiffe rentiated carcinoma of the ascending colon. A 62-year-old woman develo ped hypokalaemia and metabolic alkalosis associated with markedly elev ated serum cortisol and plasma ACTH levels. High-dose dexamethasone (8 mg/day) did not suppress increased urinary 17-hydroxycorticosteroid a nd 17-ketosteroid excretion. Barium enema and abdominal computerised t omography showed a Borrmann II type tumour in the ascending colon, mul tiple metastatic nodules in the liver and bilateral enlargement of the adrenal glands. Histological examination of the resected primary colo n cancer and metastatic liver tumour showed undifferentiated carcinoma with areas of distinct neuroendocrine, exocrine, and squamous differe ntiation. ACTH production by the tumour was confirmed by radioimmunoas say and immunohistochemistry. This is a unique case report of carcinom a of the colon with distinct multidirectional differentiation causing ectopic ACTH syndrome.