Occult Carcinoma in Thyroid Adenoma

Abstract

1111 cases of thyroid adenoma surgically removed at the National Cancer Institute of Milan from 1928 to 1966 were examinated in order to search for areas of occult carcinoma. In each case three to five istological sections were examinated. The diagnosis of malignancy was based upon histological criteria, i. e. infiltration of the tissues, invasion of basal membrane, invasion of venous vessel or of the thyroid capsule; the cytological criteria were considered by themself not sufficient to state the diagnosis of malignancy. Twenty cases (1.8%) showed microscopic areas of carcinoma. This rate does not seem to be higher than the rate of occult carcinoma in clinically normal thyroids as reported in the medical literature.