Epstein-Barr Virus-Positive Plasmablastic Lymphoma Arising in the Anal Canal of an Immunocompetent Patient.

This case report describes a 57-year-old immunocompetent male diagnosed with Epstein-Barr virus (EBV)-positive plasmablastic lymphoma (PBL), a rare and aggressive subtype of diffuse large B-cell lymphoma (DLBCL), presenting in the anal canal. PBL is most commonly seen in immunocompromised patients, particularly those with a human immunodeficiency virus (HIV) infection; its presence in immunocompetent individuals is exceedingly rare. The patient presented with persistent anal pain, prompting a comprehensive diagnostic workup. Histopathological and immunohistochemical analysis confirmed PBL, with a high proliferation index and EBV-encoded RNA (EBER) positivity. The patient initially responded to dose-adjusted rituximab, etoposide, prednisone, vincristine, cyclophosphamide, and doxorubicin (DA-R-EPOCH) chemotherapy, with a reduction in mass size and metabolic activity. However, the disease relapsed, requiring further treatment with ifosfamide, carboplatin, and etoposide (ICE) chemotherapy, followed by consolidation with autologous stem cell transplantation (ASCT), after which the patient remained in remission for six months. This report not only discusses the clinical and pathological findings but also explores the interplay between EBV and the immune system in tumor development. The case underscores the need for heightened clinical suspicion and the future potential for immunotherapeutic and EBV-targeted therapies for patients with EBV-positive PBL.