Hepatosplenic T-cell Lymphoma : Introduction
Hepatosplenic T-cell lymphoma (HSTCL) is an aggressive subtype of post-thymic extranodal T-cell lympoma which predominantly involves liver, spleen, and bone marrow with a sinusoidal pattern of infiltration. There is no lymphadenopathy. The cell of origin is non-activated cytotoxic T-cells, usually from the gamma-delta subset. Rare cases with alpha-beta phenotype have also been reported. The tumor cells show recurrent cytogenetic abnormality consisting of isochromosome 7q and frequent mutations in STAT5B gene. HSTCL is rare and makes up 1% to 2% of all peripheral T-cell lymphomas. It is a malignancy of young adults, with a median age at presentation of 35 years. There is male predominance. Risk Factors: Some cases of HSTCL have occurred in immunodeficient states, including the following: long-term immunosuppressive therapy for solid organ transplantation, acute myeloid leukemia, EBV-positive lymphoproliferative disorder, falciparum malaria infection, young patients with inflammatory bowel disease receiving a combination of azathioprine and infliximab (anti-tumor necrosis factor), rheumatoid arthritis or psoriasis patients on TNF-alpha inhibitors and immunomodulators, and pregnancy. This low magnification image of HSTCL in spleen shows expansion of red pulp due to diffuse infiltration of the cords and sinuses by the neoplastic cells with preservation of architecture. White pulp areas are reduced.