Clinical characteristics distinguishing hereditary from sporadic medullary thyroid carcinoma. Treatment implications.

Distinctive differences between the hereditary and sporadic varieties of medullary thyroid carcinoma include the uniform bilaterality, consistent association of C cell hyperplasia, and the frequent association with other endocrine lesions as characteristics of the hereditary type. Total thyroidectomy is required for hereditary medullary thyroid carcinoma. Lateral cervical lymph node dissections do not appear necessary for the hereditary type when not palpable, detected only by family screening, and when biopsy of midjugular lymph nodes shows no evidence of metastasis. For palpable medullary thyroid carcinoma, the eradication of all cervical locations is unlikely to result in normal or undetectable levels of serum calcitonin postoperatively, even though such appears more likely for the sporadic variety.