Hepatosplenic T-cell lymphoma

Synonyms

 Hepatosplenic γδ T-cell lymphoma

 Definition

 Hepatosplenic T-cell lymphoma is a systemic neoplasm comprised of medium-sized cytotoxic T-cells that show a significant sinusoidal infiltration in the liver, spleen, and bone marrow.

 Epidemiology

 This lymphoma is rare, comprising less than 5% of all cases, and is most common in young adults and adolescents. A distinct male gender preference has been described.

Clinical Features

 Etiology

 The cell of origin for this disease is an immature cytotoxic T-cell clonally expressing the γδ T-cell receptor. This disease is seen more often in immunosuppressed solid organ transplant recipients, an association that has led to the hypothesis that long-term immune stimulation in the setting of immunosuppression is the causative agent.

 Clinical Presentation

 The typical clinical finding in a patient with hepatosplenic T-cell lymphoma is hepatosplenomegaly.

 Laboratory Findings

 The constellation of thrombocytopenia, anemia, and leukocytosis is common in patients with hepatosplenic T-cell lymphoma. The discovery of neoplastic cells in peripheral blood is often a finding late in the clinical course.

 Sites of Involvement

 The spleen and liver are always involved, with bone marrow involvement frequently present. Nodal involvement is exceedingly rare.

 Morphology

 The neoplastic cells in this disorder show a monotonous appearance, with a small amount of cytoplasm and inconspicuous nucleoli.

 Spleen and liver

 This disease shows a distinct sinusoidal pattern of infiltration which spares the splenic white pulp and hepatic portal triads.

 Bone marrow

 While the bone marrow is commonly involved, the detection of the neoplastic infiltrate may be difficult due to diffuse, interstitial pattern. Immunohistochemistry can aid in the detection of this lymphoma.

 Peripheral blood

 Cells of a similar morphology observed in solid organs are observed in peripheral blood.

 Molecular Findings

 Immunophenotype

 The immunophenotype for hepatosplenic T-cell lymphoma is a post-thymic, immature T-cell.

Genetic Findings

 Clonal rearrangement of the γ gene of the T-cell receptor is the hallmark of this disease. A few cases have shown rearrangement of the T-cell receptor β gene. Isochromosome 7q has been observed in all cases described so far, sometimes in conjunction with other chromosomal abnormalities such as trisomy 8.