Review: Medullary carcinoma of the thyroid: radiographic features of a unique tumor

Medullary carcinoma of the thyroid is a unique neoplasm characterized by consistent production of a hormonal marker, calcitonin, calcification of both primary and metastatic foci, and association with other endocrine neoplasms. It accounts for 3.5%--10% of all thyroid malignancies. First described by Hazard et al. [1] in 1959, this neoplasm has become the focus of increasing clinical and experimental investigation. It occurs both sporadically and in families. When familial, it is seen as a component of the multiple endocrine neoplasia type II (MEN-II) syndromes. Interest in medullary carcinoma of the thyroid far exceeds that warranted by its infrequent occurrence. Over 200 articles dealing with this tumor have appeared in the medical literature in the last 10 years. This may be attributed to the number of distinctive properties of the tumor: the familial occurrence when associated with endocrinopathies, the propensity to produce amyloid, and the great synthetic capability for the biogenic amines calcitonin, serotonin, histaminase, and prostaglandins. Of greatest importance is the value of calcitonin radioimmunoassay for detecting patients with the tumor even though it may be evident clinically. Fifty-three patients with surgically and biochemically proven medullary carcinoma were evaluated and followed at Duke University Medical Center from 1968 to 1981. Ten patients with sporadic tumor, 37 with MEN type IIa, and six with MEN type IIb prompted this review. They will be used to illustrate the varied and sometimes characteristic radiographic manifestations of medullary carcinoma of the thyroid. This tumor has a spectrum of radiographic features in multiple organs that, when familial, facilitate its recognition and treatment.