S-100 protein-positive sinusoidal large cell lymphoma.

A subset of T lymphocytes has recently been reported to express S-100 protein. We report a case of S-100-positive peripheral T-cell lymphoma with a sinusoidal pattern of lymph node involvement. The immunophenotypic profile was T1+, T3+, T4+, T6-, T8-, T11+. The 12-year-old boy presented with thrombocytopenia and splenomegaly and was found to have malignant lymphoma involving the para-aortic lymph nodes, spleen, and bone marrow. The disease ran a rapidly fatal course.