Hepatosplenic T-cell lymphoma: A clinicopathologic review with an emphasis on diagnostic differentiation from other T-cell/natural killer-cell neoplasms

Hepatosplenic T-cell lymphoma is a rare, aggressive Tcell lymphoma, characterized by hepatosplenic sinusoidal infiltration of monotonous, medium-sized, nonactivated cytotoxic T cells, usually of γ/δ T-cell receptor type. Hepatosplenic T-cell lymphoma occurs more frequently in immunocompromised patients, especially in those receiving long-term immunosuppressive therapy. Patients usually manifest hepatosplenomegaly without lymphadenopathy. The bone marrow is also involved in two-thirds of cases and is often accompanied by circulating lymphoma cells, which, along with anemia and thrombocytopenia, may raise suspicion for acute leukemia. The differential diagnosis includes aggressive natural killer-cell leukemia, T-large granular lymphocytic leukemia, T-lymphoblastic leukemia, enteropathy-associated T-cell lymphoma type II, primary cutaneous γ/δ T-cell lymphoma, other peripheral T-cell lymphomas, myelodysplastic syndrome, and infectious mononucleosis. The diagnosis is usually established from the combination of clinical findings, histologic features, and immunophenotype, although cytogenetic/ molecular studies are occasionally needed. Hepatosplenic T-cell lymphoma exhibits a dismal clinical course with a poor response to currently available therapies.