Extranasal extranodal NK/T-cell lymphoma associated with systemic lupus erythematosus.

Increased incidence of lymphoproliferative disorders is reported in patients with autoimmune diseases, majority of which have a B-cell phenotype and are pathogenetically associated with the reactivation of Epstein-Barr virus (EBV). However, EBV-associated T/NK-cell lymphoma has hardly been reported. We present the case of a 68-year-old-woman, who had been diagnosed with systemic lupus erythematosus (SLE) 28 years back and was treated with various immunosuppressive agents including steroids, cyclophosphamide, and tacrolimus. She presented with a progressively worsening swelling of the right thigh for the last few months. Radiological examination revealed an intramuscular bulky tumor without any other lesions and the biopsy results led to a diagnosis of extranodal NK/T-cell lymphoma, nasal type (ENKL). Concurrent chemoradiotherapy resulted in a complete response, which has been sustained for more than 2 years without requiring additional therapy. After the initiation of chemotherapy, SLE did not worsen with the administration of low-dose corticosteroids. To the best of our knowledge, this is the first case report of a localized extranasal ENKL developing in a patient with SLE.