Inherited medullary microcarcinoma of the thyroid - A study of 11 cases

The authors report 11 patients with genetically determined medullary microc arcinomas. Nine patients were either children or adolescents and two patien ts were young adults. The youngest patient was 7 years old and the oldest w as 34 years of age (mean age, 15.4 yrs). The preoperative diagnosis was bas ed on family history and elevated serum calcitonin levels. In addition, six patients had RET protooncogene mutations in exons 10, 11, and 16. Two pati ents who had the RET protooncogene mutations did not have serum calcitonin measurements. Nine patients had bilateral medullary microcarcinomas (<1.0 c m), whereas the two patients with unilateral tumors demonstrated multifocal disease. The principle microscopic differences between these genetically d etermined medullary microcarcinomas and larger sporadic (>1 cm) medullary c arcinomas were the low incidence of stromal desmoplasia and amyloid deposit ion, the high incidence of C-cell hyperplasia, and the low incidence of lym ph node metastases. Only one patient, a 34-year-old man, presented with lym ph node metastases. All patients remain disease free 11 to 70 months after diagnosis. This small series of thyroid microcarcinomas illustrates the imp act molecular diagnostics is having on the management and prognosis of gene rically determined medullary carcinoma.