Immunohistological quantitative analysis of S100 protein-positive cells in T-cell malignant lymphomas, especially in adult T-cell leukemia/lymphomas.

S100 protein-positive cells (S100+ cells) in 36 cases of T-cell lymphoma (T-ML) in the lymph node and 15 cases of T-ML in the skin were analyzed immunohistologically in order to study their quantitative features in adult T-cell leukemia/lymphoma (ATLL). The T-MLs were categorized according to the updated Kiel classification, and the T-cell pleomorphic type (Pleo) was subcategorized into 3 subtypes: Pleo-ATLL, Pleo-clear and Pleo-others. The population of S100+ cells and the first to fifth minimal distances of every S100+ cell were measured on micrographs of paraffin sections that had reacted to anti-S100 protein antibody according to the ABC method. Lymphoblastic and chronic lymphocytic leukemia types showed low populations of S100+ cells and long values of the first minimal distance. T-zone lymphoma without follicles and angioimmunoblastic lymphadenopathy with dysproteinemia-type T-ML had high populations and low values of the first minimal distance. Among the three subtypes of Pleo in the lymph node, Pleo-ATLL gave the highest population and the shortest value of the first minimal distance of S100+ cells, but this trend was not found in the skin. Clusters of more than five S100+ cells were more common in the Pleo-ATLL subtype than in the other two subtypes. The increase and clustering of S100+ cells in Pleo-ATLL suggests that the lymphoma cells act on S100+ cells as a helper.(ABSTRACT TRUNCATED AT 250 WORDS)