ISOCHROMOSOME 7Q - THE PRIMARY CYTOGENETIC ABNORMALITY IN HEPATOSPLENIC GAMMA-DELTA T-CELL LYMPHOMA

Malignant lymphomas often have complex, nonrandom chromosomal abnormal ities. Hepatosplenic gamma delta T cell lymphoma (gamma delta TCL) is an unusual post-thymic T cell lymphoma that primarily involves river a nd spleen, often in young adult males. Few cases have had cytogenetic analysis. We report a consistent isochromosome 7q [i(7q)] abnormality in three cases of hepatosplenic gamma delta TCL, one with i(7q) as the sole abnormality at presentation. Three patients, 15-, 37- and 65-yea r-old males, presented with hepatosplenomegaly and fevers. Histopathol ogic, immunophenotypic, and molecular genetic studies supported the di agnosis. Spleen, liver, and bone marrow contained sinusoidal infiltrat es of atypical lymphoid cells of T cell immunophenotype. PCR performed on two cases demonstrated clonal T cell receptor gamma gene rearrange ments. Cytogenetic analysis of bone marrow showed i(7q) as the sole ab normality at presentation in one case. The second case showed i(7q) in addition to two normal chromosomes 7, and other structural and numeri cal abnormalities. The third case showed i(7q) and a deletion in the l ong arm of chromosome 11. These findings support the proposal that i(7 q) represents the primary nonrandom cytogenetic abnormality in hepatos plenic gamma delta TCL, and plays a role in its pathogenesis.