RÉSUMÉ
Posttransplant lymphoproliferative disorders (PTLDs) comprise a spectrum of complications that affect immunocompromised patients following hematopoietic stem cell transplantation or solid organ transplantation. Its incidence varies depending on the transplanted organ, occurring in approximately 2.3% of kidney transplantations. A 31-year-old woman was referred to the Dental Clinic of the State University of Western Paraná for evaluation of an oral lesion. Her medical history revealed a previous diagnosis of hypertension, Epstein-Barr virus (EBV) seropositivity, and kidney transplantation 12 years prior. She was under standard immunosuppressive therapy. Intraoral examination identified a gingival necrotic lesion with extension to the posterior right lower alveolar bone. An incisional biopsy was performed. Histologic examination showed lymphocytic proliferation of cells with small and hyperchromatic nuclei, atypical mitosis, and cells with large and pale nuclei showing prominent nucleoli permeating connective tissue, muscle fibers, and adipocytes. Correlation of clinical, histologic, and immunohistochemical findings led to a diagnosis of polymorphic EBV-associated PTLD rich in B and T cells.