Thyroid multifocal granulomatous folliculitis (palpation thyroiditis): An immunocytochemical study.

We analyzed lymphoid cell populations from thyroid multifocal granulomatous folliculitis (palpation thyroiditis) with a panel of antibodies in order to assess the nature of the immunologic process underlying this otherwise clinically insignificant condition as compared with other specific types of thyroiditis. In general, T lymphocytes predominated over B lymphocytes as shown by the extent of the staining with UCHL-1 (CD45RO or CD3 and L26 (CD20) antibodies, respectively. The ratio of kappa-to-lambda-containing plasma cells was 1.4 to 1. Histiocytes, macrophages, and multinucleate giant cells were all found to stain consistently strongly with KPI (CD68) and, when intraluminal, not infrequently also for thyroglobulin, probaby due to colloid phagocytosis. The differing patterns of light chain restriction observed in multifocal granulomatous folliculitis as compared with Riedel's thyroiditis and Graves disease thyroiditis, for instance, may reflect differences in the nature of the underlying immune response.