Orbital T-cell lymphoma in human T-cell leukemia virus-I infection.

This is the first report of orbital involvement in systemic adult T-cell leukemia/lymphoma (ATLL). The etiologic agent of ATLL is the human T-cell leukemia virus-I (HTLV-I), the first retrovirus demonstrated to induce cancer in humans. The diagnosis of ATLL is based on characteristic clinicopathologic features in combination with serologic or virologic evidence of HTLV-I infection. Serum antibodies to HTLV-I were identified by immunofluorescent microscopy. Viral particles characteristic of HTLV-I were found in a culture of the patient's peripheral blood lymphocytes. The patient was a native of the Caribbean, one of the known endemic foci of HTLV-I infection. Adult T-cell leukemia/lymphoma should be considered in the differential diagnosis of orbital T-cell lymphomas.