[Proliferative activity of thyroid papillary microcarcinoma]

Papillary microcarcinoma (PMC) of the thyroid is its papillary carcinoma (TPC), which measures 1 cm or less (WHO). According to autopsy data, the incidence of PMC that cannot be identified during a patient's life is 1 to 36%. Proliferative activity was analyzed in 75 cases of PMC, by immunohistochemical assays using antibodies to the proliferation markers Ki-67, cycline DI, and MCM2 in paraffin block slides. The proliferative activity of PMC with a size of 1-7 mm is much decreased as compared with that with a size of 8-10 mm and TPC with a larger size. The proliferative activity of PMC with a size of 8-10 mm does not differ from that of PPC of a larger size. The proliferative activity of PMC does not correlate with the presence of tumor metastases or depend on the presence of a tumor capsule, but it is significantly increased in the tumors with some high-grade component PMC more than 50% and in those with invasion.