Bone marrow-restricted involvement of T-cell granular lymphocyte leukemia

A 66-year-old female was referred to our hospital with bone pain and progressive pancytopenia with granular lymphocyte infiltration only in the bone marrow (BM). Flow cytometric and histological analyses revealed that these cells were positive for CD3, TCRalphabeta, granzyme B, and the diagnosis of T-cell granular lymphocyte leukemia (T-GLL) with myelofibrosis was made. These BM granular lymphocytes were greatly ruffled and showed the CD3/CD20 double positive phenotype, which was not detected in the peripheral blood. The patient was treated with a single course of fludarabine followed by a favorable clinical course for 3 months. Many of the BM lymphocytes displayed almost normal appearance after treatment, however, the number of lymphocytes in the BM did not decrease and these were still CD3/CD20 double positive. This is an overlap case of T-GLL and peripheral T-cell lymphoma, unspecified (PTCLu).