ABSTRACT
BACKGROUND: Papillary thyroid carcinoma has become increasingly prevalent over the years. Avoiding unnecessary treatments and the risk of complications is fundamental, as well as understanding the mechanisms of tumor progression and conditions that indicate a worse prognosis. The evaluation of the tumor microenvironment can allow the understanding of how the immune system organizes itself to contain the neoplastic advance. METHODS: We compared characteristics related to the lymphocytic subpopulations in the thyroid tumor microenvironment and in the lymph nodes in two groups, with and without lymph node involvement. RESULTS: From four hundred cases followed up at a reference service in thyroid cancer, we selected thirty-two, of which thirteen cases did not present lymph node metastasis (N0 group) and nineteen had lymph node involvement (N1 group). Clinical data were collected, and immunohistochemical reactions were performed for CD4, CD8, FoxP3, CD25 and CD20 markers in lymph nodes and peritumoral infiltrate. We found that the N1 group had a larger tumor size, higher risk staging, higher frequency of extrathyroidal extension, shorter disease-free time and higher expression of CD4+ T lymphocytes in the lymph nodes; however, there was no difference in the expression of other markers or in the pattern of lymphocytic distribution in the lymph node. CONCLUSION: In cervical lymph nodes, the higher frequency of T CD4+ lymphocytes, would be related to the presence of metastasis, while there were no differences in lymphocytic subpopulations in thyroid tumor microenvironment. The absence of changes in unaffected lymph nodes could not predict any tumor behavior.
