Cytotoxic hepatosplenic gamma delta T-cell lymphoma following acute myeloid leukemia bearing two distinct gamma chains of the T-cell receptor. Biological and clinical features

Background and Objectives, Hepatosplenic gamma delta T-cell lymphoma is a r are entity of peripheral T-cell lymphomas. We characterized in detail the f irst case of hepatosplenic gamma delta -T-cell lymphoma following acute mye loid leukemia. Design and Methods. Hepatosplenic gamma delta -T-cell lymphoma was diagnose d in a woman who had been in complete remission (CR) of acute myeloid leuke mia (AML) for two years. Improvement but no objective response of the disea se was observed after various types of chemotherapy, CR was achieved after related donor stem cell transplantation. Thirteen months later relapse of h epatosplenic gamma delta T-cell lymphoma was diagnosed. While being prepare d for a second transplantation the patient developed meningeal lymphoma and died, The patients lymphoma cells were studied by immunologic, functional and molecular techniques. Results. Lymphoma cells expressed the gamma delta T-cell receptor (TCR), CD 2, CD3, CD5, CD7, CD38, CD45, CD161 (NKR-P1), TIA and Ki67, Further analysi s revealed expression of V delta1 and two distinct TCR gamma chains, V gamm a3 and V gamma9, by the malignant cell clone. The clonality of the T-cells was confirmed by reverse transcriptase polymerase chain reaction (RT-PCR) f ollowed by sequencing of TCR V gamma3, V gamma9 and V gamma1 junctional reg ions. Clone-specific PCR was negative at diagnosis of AML and was positive at all times during follow-up of the hepatosplenic gamma delta T-cell lymph oma. The lymphoma cells mediated strong natural killer cell-like cytotoxic activity, possibly explained by expression of CD161 and a lack of killer in hibitory receptor. Interpretation and Conclusions. Several so far undescribed features were ob served in this case of hepatosplenic gamma delta T-cell lymphoma, such as T -cell lymphoma following AML, expression of two distinct T-cell receptor ga mma -chains, and an unexpected cytotoxic phenotype, (C)2000, Ferrata Storti Foundation.