Encapsulated papillary carcinoma of the thyroid gland: clinicopathological and cytofluorometric study in comparison with non-encapsulated papillary carcinoma.

Clinicopathological and cytofluorometric studies were performed on nine encapsulated (EPC) and 23 non-encapsulated (non-EPC) carcinomas of the thyroid gland. The average age of the patients with EPC was 33 years, which was significantly younger than that of those with non-EPC. The average tumor size of EPC was twice as large as that of intraglandular non-encapsulated carcinoma. All patients with EPC were alive without disease, but three out of 23 patients with non-EPC had a recurrence of the disease or died. Cytofluorometric studies showed that the mean nuclear DNA content and percentage of tumor cells in the S-G2M phase of EPC were lower than that of non-EPC. According to the DNA histogram pattern, all EPC showed distinct modal DNA values in the diploid or near diploid region of normal cells. However non-EPC, especially extra-glandular non-encapsulated papillary carcinoma, showed a wide variety of DNA histogram patterns. The present study suggested that EPC is a distinct subtype of papillary carcinoma of the thyroid gland clinicopathologically and that cytofluorometrically it is different from non-EPC.