Comparing Nodal with Primary Tumor Desmoplasia Uncovers Metastatic Patterns in MEN 2B.

While primary tumor desmoplasia is a powerful biomarker of node metastases in sporadic medullary thyroid cancer (MTC), information for hereditary MTC is sparse. This proof-of-concept study, comprising three consecutive children with multiple endocrine neoplasia 2B, evaluated simultaneously the metastatic behavior of multiple primary thyroid tumors of disparate size and extent of desmoplasia within patients. Altogether, MTC typically involved the ipsilateral central neck before spreading to the ipsilateral lateral and the contralateral neck. MTC in the upper lobe leaped the ipsilateral central neck to invade the ipsilateral lateral neck. Unlike the desmoplasia-positive 6-mm high-grade and 7-mm low-grade primary thyroid tumors, the desmoplasia-negative 8-mm, 11-mm and 16mm low-grade primary thyroid tumors did not spread to ipsilateral neck nodes. With extranodal growth, the extent of nodal desmoplasia was greater than with intranodal growth. This proof-of-concept study suggests that primary tumor desmoplasia is an equally powerful biomarker of node metastasis in hereditary MTC.