[Medullary carcinoma of the thyroid. Familial variety]

A patient who consulted because of diarrhea was diagnosed of thyroid medullar carcinoma (TMC) associated to pheochromocytoma. All members of his family were studied for a possible family variety of TMC with a genetic origin. In the 21 family members studied basal and calcium-pentagastrin stimulated calcitonin levels were determined and parathyroid and adrenal gland function were explored to rule out pheochromocytoma. Elevated levels of calcitonin agreed with pathological findings of TMC. Pheochromocytoma carriers had altered catecholamines and an abnormal abdominal CT scan. The clinical, analytical and radiologic findings in the four affected family members are described. The histopathological study revealed a pheochromocytoma in one case and bilateral TMC in two cases. The cytology of aspiration biopsy samples was positive for TMC in three cases. The importance of calcitonin determinations is emphasized as well as the obligatory determination of catecholamines and adrenal CT scan in order to rule out the coexistance of pheochromocytoma. The reasons for not utilizing gammagraphy with meta-iodine benzyl guanidine in these four cases are also explained.