[A unique case of severe ACTH-dependent Cushing's syndrome due to ectopic corticotropin production by medullary thyroid carcinoma].

Medullary thyroid carcinoma is a rare aggressive tumor of thyroid gland. Due to its neuroendocrine origine medullary thyroid carcinoma can be the source of ectopic production of different peptides and hormones. We describe a unique case of severe ACTH-dependent Cushing's syndrome due to ectopic corticotropin production by medullary thyroid carcinoma in a male patient of 39 years old with calcitonin level more than 4000 pg/ml (<11,8), thyroid nodule, multiple neck jugular and central lymphnodes. The potassium level was 1,34 mmol/l (3,5-5,1), hypercortisolemia up to 1613,2 nmol/l (185-624) with elevated level of ACTH up to 24,7 pmol/l (1,03-10,74). After the correction of water and electrolytes disorders an operation was performed - thyroidectomy, central and lateral neck dissection. Postoperative calcitonin decreased to 126 pg/ml (<11,8), calcium and parathormone blood levels remained normal. The potassium level didn't decrease without any pharmacological treatment. There was a sharp fall in postoperative blood levels of cortisol and ACTH. The hormonal replacement treatment with hydrocortisone was induced. Morphological examination showed medullary carcinoma with ACTH production in tumor nodule, with metastatic neck lymph nodes. Thus this is a rare case and successful treatment of patient with severe hypercortisolism by thyroidectomy and neck lymphnodes dissection.