Intermediate lymphocytic lymphoma of the thyroid. An immunologic and immunohistologic study

Four cases of thyroid lymphomas are presented showing curious histologic difficult to distinguish from severe lymphocytic thyroiditis by routine histologic study alone. The age of the patients ranged from 39 to 63 years. Three female patients suffered from autoimmune (lymphocytic) thyroiditis for 2 to 20 years until the present illness. A male patient had no history of thyroiditis. Rapid growth of struma in these patients suggested an evolution of malignant lymphomas. Histologic study results showed that small atypical lymphoid cells with slightly irregular and indented nuclear contour surrounded randomly distributed secondary follicles as a wide mantle. Immunohistologic staining showed that these atypical small lymphoid cells expressed surface properties intermediate between mantle-zone lymphocytes and germinal center cells with a restricted expression of kappa chain in three cases. Stages of tumors were stage I in three cases and stage II in one case. The findings demonstrated were intermediate lymphocytic lymphomas of the thyroid.