Abstract
A 53-year-old male with Cushing's syndrome due to ectopic ACTH production from medullary carcinoma of the thyroid was reported. The clinical course and results of detailed endocrinological studies and immunohistochemical findings about the cancer tissue were described.
An abnormally high concentration of calcitonin, ACTH and β-MSH in both plasma and cancer tissues (thyroid, lymph nodes and liver) were documented by radioimmunoassay. Urinary 17-OHCS was as high as 38.4 mg/day to 56.0 mg/day and showed no suppression following dexamethasone 8 mg/day administration. Oral metyrapone (3 g/day) caused no response in urinary 17-OHCS. Parallel increments in plasma calcitonin, ACTH and β-MSH were observed following calcium and gastrin loading.
Total thyroidectomy with modified radical neck dissection caused minimal changes of plasma levels of calcitonin, ACTH and β-MSH and no improvement in the clinical manifestations of Cushing's syndrome. An aortogram revealed metastatic tumors in the liver. A second operation, total adrenalectomy, resulted in an improvement of the clinical and laboratory findings such as hypokalemia, high blood pressure, muscle atrophy and moon face.
Immunofluorescent study showed different distribution patterns in calcitonin-and ACTH-positive cells in the primary focus but similar patterns in the liver metastasis.
