Epstein-Barr virus-associated extranodal NK/T-cell lymphoma following mosquito bites in an elderly patient without prior hypersensitivity.

We describe a 73-year-old woman who developed fever and inflammation with ulceration at the site of mosquito bites in the lower thigh. Soon she developed disseminated skin lesions characterized by redness, induration, and local heat. Some lesions showed necrosis and ulceration, including those located in the nasal cavity. She had no history of hypersensitivity to mosquito bites, and the serum IgE concentration was within the reference range. A skin biopsy specimen from the lower thigh adjoining the mosquito bites was diagnosed pathologically as showing extranodal NK/T cell lymphoma, nasal type. Southern analysis of the biopsy specimen showed an oligoclonal band representing Epstein-Barr virus (EBV) DNA. Bone marrow examination revealed infiltration by lymphoma cells and marked hemophagocytosis. The patient underwent three cycles of chemotherapy with carboplatin, etoposide, ifosfamide, and dexamethasone (DeVIC), but died of lymphoma progression during treatment. We speculate that, rather than an allergic reaction, this late-life occurrence of hypersensitivity to mosquito bites might represent lymphoproliferative disease induced by a direct action of mosquito salivary gland secretions on EBV- infected NK cells.