The occurrence of occult thyroid carcinoma at autopsy was examined in 507 consecutive autopsies performed over one-year in subjects without clinical evidence of thyroid cancer, from different regions of Italy, including areas of endemic goiter. We found 54 (10.65%) occult thyroid carcinomas. In 37 cases the histologic pattern was of the papillary type, with diameter ranging between 176 and 6000 microns, 12 of these cases showed a typical papillary pattern, 6 had a marked fibrosis, 2 had a cystic pattern, one showed a lymphoid stroma, and 17 had a follicular pattern. The remaining 17 cases were medullary carcinomas, with a diameter ranging from 50 to 1600 microns. The percentage of occult thyroid carcinomas reported in the present study may constitute real value of the occurrence of this tumor in the Italian population
