Expression of CD9 and CD82 in papillary thyroid microcarcinoma and its prognostic significance

Introduction: papillary thyroid microcarcinoma is a well-known malignant neoplasm with good prognosis. The known prognostic factors are patient's age, multifocality, and extrathyroidal extension. CD9 and CD82, members of the tetraspanin family, are expressed in numerous cancer cells and play many roles associated with the cellular process. Material and methods: we investigated the immunohistochemical expression of CD9 and CD82 in papillary thyroid microcarcinoma and analysed the clinicopathological and prognostic significance. For the retrospective analysis, we collected the cases of 553 PTMC patients who had undergone thyroidectomy. Results: The group with lymph node metastasis showed higher immunostaining intensity for CD9 than the group without metastasis (p = 0.002). In multivariate analysis, high CD9 intensity (OR = 1.58 in 3+, p = 0.0025) correlated with lymph node metastasis. Conclusion: We suggest CD9 as a predictive prognostic factor for lymph node metastasis in PTMC.