Hepatosplenic T cell lymphoma pathophysiology

Sites of Involvement
The spleen and liver are always involved, with bone marrow involvement frequently present. Nodal involvement is exceedingly rare. Jaffe E.S., Harris N.L., Stein H., Vardiman J.W. (eds): ''World Health Organization Classification of Tumors. Pathology and Genetics of Tumours of Haemopoietic and Lymphoid Tissues.'' IARC Press: Lyon 2001

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.

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.