We herein describe what is, to the best of our knowledge, the first case of T/HRBCL-associated ITP successfully treated by chemotherapy. Case report A 54-year-old man presented to Kobe City Medical Center LTBR antibody General Hospital (Kobe, Japan) in May 2017 with a fever of 38.9C, bilateral cervical and right axillary lymphadenopathies, Silicristin petechial purpura on the upper and lower limbs and intraoral mucosal hemorrhage. however, there were Silicristin no pathological cells or phagocytic cells. The patient was diagnosed with ITP; concurrently, he was also diagnosed with T/HRBCL via lymph node biopsy, and was treated accordingly with a chemotherapeutic regimen comprising rituximab, cyclophosphamide, doxorubicin, vincristine and prednisolone. Prompt reduction in the size of the superficial lymph nodes and an increase of the platelet count were observed simultaneously. To the best of our knowledge, this is the first report of T/HRBCL complicated by ITP. The findings strongly suggest a causative association between ITP and T/HRBCL. Keywords: immune thrombocytopenic purpura, T-cell/histiocyte-rich B-cell lymphoma, chemotherapy, R-CHOP, recurrence Introduction Immune thrombocytopenic purpura (ITP) is characterized by antibody- and immune-precipitated platelet destruction, occasionally causing life-threatening hemorrhage. ITP is a frequent complication of hematological malignancies, particularly chronic lymphoid leukemia (1); however, it is less common in non-Hodgkin lymphoma (NHL), affecting only 0.76% of the patients (2). Thus, the etiology and treatment of NHL-associated ITP have not been clearly determined, although this is a potentially life-threatening condition that is difficult to manage. Only 10 cases of diffuse large B-cell lymphoma (DLBCL), which is the most common type of NHL, complicated by ITP have been reported to date (2). T-cell/histiocyte-rich B-cell lymphoma (T/HRBCL) is an uncommon variant of DLBCL characterized by a limited number of atypical B cells in a background of abundant T cells and histiocytes (3,4). A case of T/HRBCL complicated by symptoms mimicking autoimmune disease was recently reported (5). We herein describe what is, to the best of our knowledge, the first case of T/HRBCL-associated ITP successfully treated by chemotherapy. Case report A 54-year-old man presented to Kobe City Medical Center General Hospital (Kobe, Japan) in May 2017 with a fever of 38.9C, bilateral cervical and right axillary Silicristin lymphadenopathies, petechial purpura on the upper and lower limbs and intraoral mucosal hemorrhage. The patient reported a history of fever and lymphadenopathy that started 1 month prior to hospitalization, and he was admitted to our hospital for thorough examination and treatment. The patient had no symptoms indicative of collagen disease, such as skin rash or joint pain. His liver and spleen were not palpable. The laboratory data on admission are summarized in Table I. Briefly, complete blood count and biochemical tests revealed the following: Hemoglobin, 12.2 g/dl; platelet count, 0.5109/l; reticulated platelets, 59%; white blood cell count, 10.1109/l; lactate dehydrogenase (LDH), 315 U/l; soluble interleukin-2 receptor, 25,045 U/ml; platelet-associated immunoglobulin G, 462.2 ng/107 cells; antinuclear antibody, negative; and Epstein-Barr virus antibody and human immunodeficiency virus, negative. Computed tomography examination revealed bilateral cervical (25 mm), bilateral axillary (15 mm), mediastinal (19 mm) and para-aortic (20 mm) lymphadenopathies (Fig. 1). A bone marrow biopsy revealed mild hypercellularity, with an increase in the number of megakaryocytes; however, pathological lymphocytes or phagocytes were not identified. Flow cytometric analysis and molecular analysis confirmed the absence of clonal malignant cell invasion. The suspected diagnosis was immune thrombocytopenic purpura (ITP), based on the thrombocytopenia, normal white blood cell count, mild anemia, increase in reticulated platelets, and lack of evidence of malignant cell invasion, hemophagocytic syndrome, or other cause of thrombocytopenia. Intravenous immunoglobulins were administered, but did not improve the platelet count. A biopsy of a right axillary lymph node was performed and the lymph node structure was found to be almost completely effaced by a diffuse infiltrate (Fig. 2A). A small number of scattered large atypical cells were found among numerous mature lymphoid cells (Fig. 2B). Immunohistochemical examination revealed expression of CD20 on the large malignant cells and CD3 on the small cells of the background. CD30, CD15 and Epstein-Barr virus early small ribonucleic acids were absent in both the large and small lymphocytes (Fig. 2C and D). The infiltrating large cells were positive for but negative for light chain (Fig. 2E-G). Immunoglobulin heavy chain rearrangement was not detected, and the karyotype Silicristin of the lymphoma cells was 46,XY. Therefore, the patient was diagnosed with T/HRBCL of.