Intratumoral lymphatics and lymph node metastases in papillary thyroid carcinoma.

OBJECTIVE To examine the relationship between lymphatic vessel density and clinical and pathological variables in patients with well-differentiated papillary thyroid carcinoma. SUBJECTS Clinical information was retrieved on 109 previously untreated patients with well-differentiated papillary thyroid carcinoma treated with total thyroidectomy and postoperative iodine I 131 ablation. Median follow-up was 38 months. DESIGN Archived tissue specimens were sectioned and stained with hematoxylin-eosin and anti-LYVE-1 antibody, a highly specific marker for lymphatic endothelium. The size of the tumor and its multifocality were noted and lymphatic vessel density was measured by means of Chalkley point counting. RESULTS Numerous intratumoral lymphatics were seen in papillary thyroid carcinoma. There was a highly significant association between the presence of intratumoral lymphatics and the presence of neck node metastases (P<.001). There was also a significant association with male sex (P =.03) and the presence of multifocal disease (P =.05). The presence of intratumoral lymphatics remained significantly associated with the presence of nodal metastases at presentation (P =.003) on multivariate analysis. Intratumoral lymphatics were not a significant predictor of tumor recurrence (P =.42, log-rank test). CONCLUSIONS The development of intratumoral lymphatics in well-differentiated papillary thyroid carcinoma appears to be associated with the spread of tumor to regional lymph nodes. The antimetastatic potential of targeting these lymphatics may be of potential therapeutic benefit in the future.