[Composite lymphoma consisting of adult T-cell leukemia-lymphoma and diffuse large B-cell lymphoma]

Area of Science:

• Hematology
• Oncology
• Immunology

Background:

• Adult T-cell leukemia/lymphoma (ATL) is a mature T-cell malignancy associated with Human T-lymphotropic virus type 1 (HTLV-1).
• Epstein-Barr virus (EBV) is a common herpesvirus that can be implicated in lymphoproliferative disorders, including diffuse large B-cell lymphoma (DLBCL).
• Composite lymphomas, involving distinct neoplastic clones, are uncommon but present unique diagnostic and therapeutic challenges.

Observation:

• A 68-year-old man presented with back pain, lymphadenopathy, and hypercalcemia, testing positive for anti-HTLV-1 antibodies.
• Cervical lymph node biopsy revealed a mixed proliferation of CD4-positive atypical cells (consistent with ATL) and CD20/EBV-encoded RNA dual-positive atypical large cells (consistent with DLBCL).
• Molecular analysis confirmed monoclonal integration of HTLV-1 and clonal rearrangements of both T-cell receptor and immunoglobulin heavy chain genes in the same specimen.

Findings:

• A diagnosis of composite lymphoma comprising ATL and EBV-positive DLBCL was established.
• The patient achieved initial remission with chemotherapy including rituximab.
• Recurrence of ATL alone was observed eight months later, leading to the patient's death despite salvage therapy.

Implications:

• This case highlights the potential for ATL-related immunodeficiency to predispose patients to the development of EBV-associated DLBCL.
• Understanding the interplay between ATL and EBV is crucial for managing these complex hematologic malignancies.
• The findings underscore the importance of comprehensive molecular and immunophenotypic analysis in diagnosing composite lymphomas.