Dorfman and coworkers examined SEMA4D/CD100 expression pattern in 138 cases of non-Hodgkin's lymphoma (NHL) by immunohistochemistry (37); most of T-cell NHL cases were positive for SEMA4D, whereas B-cell lymphomas were consistently negative for SEMA4D, including cases of small lymphocytic lymphoma (SLL)/chronic lymphocytic leukemia (CLL), follicular lymphomas, marginal zone lymphoma, mantle cell lymphoma, and diffuse large B-cell lymphoma. The gene discussed is SEMA4D; the disease is diffuse large B-cell lymphoma.