Hepatosplenic T-cell Lymphoma

Hepatosplenic T-cell lymphoma (HSTCL) is an aggressive post-thymic extranodal T-cell lympoma predominantly involving liver, spleen, and bone marrow with a sinusoidal pattern of infiltration. It arises from non-activated cytotoxic T-cells of the gamma-delta subset. Rare cases have alpha-beta phenotype. It makes up 1% to 2% of all peripheral T-cell lymphomas. It arises in young adults (median age 35 years). Some cases occur in immunodeficiency states. It presents with hepatosplenomegaly but no lymphadenopathy. Bone marrow involvement causes cytopenias. Most patients have B symptoms, including fever, fatigue, malaise, weakness, and weight loss. There is no mediastinal or retroperitoneal lymphadenopathy. The pattern of involvement in affected organs is characteristically sinusoidal. The neoplastic cells are CD3+, CD5-neg, CD8-neg, TIA-1+, granzyme B-neg, and B-cell markers neg. Most cases show clonal rearrangement of TCR-gamma. The rare alpha-beta subtype shows rearrangement of TCR-beta gene. Mutations in STAT5B are present in 30% of cases. Cytogenetic abnormalities include isochromosome 7q (50%-70% of cases). HSTCL is an aggressive lymphoma with no long-term effective treatment options. The median survival is 16 months. Reference: Jaffe, E. S. et al (2017). Hematopathology - Second Edition. Philadelphia, PA. Elsevier.