Epstein–Barr-virus-infected Plasma Cells Infiltrating Plasma Cell Mucositis of the Oral Cavity and Larynx

Epstein–Barr virus (EBV)-infected plasma cell mucositis (PCM) presenting as concurrent oral and laryngeal lesions. A 77-year-old woman presented with gingival swelling, soreness, a dry cough, and hoarseness. Incisional biopsies of the gingiva and larynx were performed. Histological examination revealed PCM. Dramatic improvement was observed after systemic glucocorticoid administration. The serum free light chain levels were correlated with disease activity. EBV infection boosts local B cell lymphoproliferation. Various immunosuppressive states trigger direct EBV-mediated activation of B cell lymphoproliferation by suppressing the functions of T cells. This case suggests a possible pathogenetic mechanism of plasma cell lymphoproliferation of the PCM.