FDG PET / CT findings of Hepatosplenic Gamma Delta T Cell Lymphoma.

Objectives: Increased FDG uptake in the liver, spleen and bone marrow are relatively common findings seen in patients with reactive bone marrow from benign conditions such as anemia, prior chemotherapy, or viral infections. Gamma delta T cell lymphoma is a very rare, highly aggressive, and rapidly lethal T cell lymphoma which may also present with increased FDG uptake in the liver, spleen and bone marrow. The objective of this study is to review the clinical presentation and imaging findings of gamma delta T cell lymphoma, which may have a similar appearance to common benign etiologies.

Methods: We present several cases of hepatosplenic T cell lymphoma (HSTL) in patients with gamma delta T cell lymphoma. The clinical, radiographic and FDG PET / CT findings are reviewed, and compared to the current literature reports. We also illustrate the clinical, radiographic, and FDG PET findings in benign etiologies of reactive marrow from anemia or prior chemotherapy, and that of viral infections.

Results: Patients with gamma delta T cell lymphoma commonly present with unexplained signs and symptoms of a suspected hematologic malignancy. Splenomegaly and hepatomegaly with symptoms of weight loss, fevers and night sweats (B symptoms of lymphoma) may be present. Thrombocytopenia, anemia, or neutropenia are common due to splenic, liver and bone marrow involvement. The peripheral blood, however, commonly does not show abnormal T cells. The predominant FDG PET / CT imaging findings are those of splenic involvement with a markedly enlarged spleen and intense FDG uptake. Hepatomegaly and increased FDG uptake in the liver uptake are also common. Bone marrow involvement may also be present, with diffuse increased FDG uptake. Importantly, lymphadenopathy is usually absent, with the majority of patients showing morphologically normal lymph nodes with normal FDG uptake.

Conclusion: Marked splenomegaly with increased FDG uptake is a striking and conspicuous finding in hepatosplenic gamma delta T cell lymphoma. Hepatomegaly and increased FDG liver uptake, as well as increased bone marrow uptake are common findings. The absence of lymphadenopathy, with normal FDG uptake in lymph nodes is a typical finding, that is not present in the majority of patients with lymphomas. In patients with clinical signs suspicious for hematologic malignancy, a bone marrow or liver biopsy is frequently necessary to establish the diagnosis. Research Support: None.