Occult papillary thyroid carcinoma at autopsy in La Plata, Argentina.

Although clinically evident thyroid carcinoma is not a frequent neoplasm (incidence 2.7 per 100,000 persons in La Plata, Argentina), occult carcinomas are present in a high proportion of the population, but there are marked differences along geographical lines. The purpose of the present study is to establish the prevalence of occult papillary thyroid carcinoma (OPC) in La Plata. Thyroid glands obtained from 100 consecutive adult necropsies were examined. The material was fixed in buffered formaldehyde at 4 degrees C, serially sectioned at 2 mm intervals, and routinely processed. Eleven thyroid glands contained OPC, corresponding in three cases to multiple lesions. Eight carcinomas were found in 59 men (13.6%) and three in 41 women (7.3%). The ages ranged from 26 to 78 years. The neoplasms varied in size from microscopic foci to 9 mm in diameter. The prevalence rate of OPC in the present study is lower than that found in Finland, Japan, and the US, and higher than for the rest of the series recorded.