An unusual case of immunoblastic lymphadenopathy (IBL)-like T cell lymphoma with neoplastic proliferation of helper T cells, occurred during the course of myelodysplastic syndrome (MDS) is reported. A 72-year-old male, who had been suffered from pancytopenia for 4 years, was admitted to our hospital on June 15, 1985 because of generalized lymph node swelling and general malaise. Laboratory examination showed severe pancytopenia, polyclonal hypergammaglobulinemia, positive Coombs' test and elevated anti DNA antibody titer. The bone marrow was found to have hypercellularity with slightly increased myeloblasts and dysplastic changes in myeloid as well as platelet-megakaryocytic lineages which agree with a diagnosis of MDS. A lymph node biopsy specimen exhibited the typical histologic picture of IBL-like T cell lymphoma with focal proliferation of pale cells and proliferation of arborizing blood capillaries. Immunofluorescence study revealed that neoplastic cells were positive for Leu 1, Leu 3a, Leu 4, Leu 5b and HLA-DR monoclonal antibodies. Immunohistochemistry and immuo-electron microscopy also showed that proliferated pale cells had helper T cell markers. He died of respiratory failure 23 days after admission.
