[Thyroid microcarcinoma]

The WHO classification of thyroid tumors defines papillary microcarcinoma as papillary carcinoma, 1 cm or less in diameter. Many Russian and foreign authors include follicular and medullary types. The limiting size which permits a tumor to be considered microcarcinoma if it measures either 1 cm or 1.5 cm. A number of investigators terminologically use the data of a clinical observation of patients. In this connection, there is a great variety of terms used to define thyroid microcarcinoma. This tumor is a common random finding in the gland removed for various disease or examined at autopsy. According to autopsies, the incidence of thyroid microcarcinoma ranges from 1 to 36%. A great deal of papers and studies are dedicated to the etiology and pathogenesis of thyroid microcarcinoma and the potentialities of its early diagnosis and adequate treatment. However, little attention is given to the histological structure and proliferative activity of this tumor and their impact on prognosis and data are at times slightly contradictory or inadequately complete.