Neoplastic and non-neoplastic thyroid lesions in autopsy material: historical review of six decades in São Paulo, Brazil.

AIMS AND BACKGROUND The aim of the study was to report and discuss a historical series of neoplastic and non-neoplastic lesions of the thyroid gland obtained at autopsy that were examined between 1931 and 1989 at the Pathology Department of the Medical School of the University of São Paulo. METHODS Records of 145,043 cases were reviewed to select those affecting the thyroid gland. The slides of these selected cases were analyzed and classified according to the current terminology. RESULTS Non-neoplastic lesions comprised 91.62% of the cases (n = 4647), and most of them were adenomatous goiter (n = 3014). Neoplastic lesions were divided into two groups: primary and metastatic. Of the 282 primary tumors, 135 were benign and 147 were malignant. Among the malignant neoplasms, the most frequent types were follicular, papillary and undifferentiated (n = 39, 36 and 29, respectively). The most frequent tumor types among the metastatic neoplasms were lymphoproliferative processes and carcinomas (n = 67 and 34, respectively). CONCLUSIONS We conclude that, because of the high frequency of neoplastic lesions (8.38%), 68.24% of which were malignant, detailed examination of the thyroid by pathological methods should be carefully and systematically performed for the accurate detection of thyroid lesions, especially carcinomas.