Diffuse Large B-Cell Lymphoma of the Gingiva in a Patient on Long-Term Use of Methotrexate Being Treated for Psoriasis.

An 81-year-old male patient presented with a large gingival ulcer of 2 months' duration. He had been taking methotrexate, a potent anti-inflammatory/immunosuppressant, for the past 50 years to treat psoriasis. A biopsy revealed diffuse large B-cell lymphoma Epstein-Barr virus positive. Remission occurred after discontinuing the medication. Clinicians noting a non-healing ulcer in the mucosal or keratinized tissue of the oral cavity of a patient on immunosuppressants should perform a biopsy examination to rule out lymphoma or other malignancy.