Unusual Presentation of Oral DLBCL Resembling a Canine Fossa Abscess.

This report aims to describe a unique case of diffuse large B-cell lymphoma originating from the oral cavity, which presented with symptoms mimicking a canine fossa abscess. It emphasizes the importance of accurate differential diagnosis and appropriate treatment. A 64-year-old female patient visited the authors' clinic with a painful swelling in the left anterior region of the maxilla, persisting for 1 month. Initially, an abscess drainage procedure was performed, accompanied by extraction of the maxillary left canine and parenteral antibiotherapy. However, no improvement was observed during the follow-up appointment after 3 days. An incisional biopsy was then conducted under local anesthesia, leading to a histopathologic diagnosis of diffuse large B-cell lymphoma. The patient is currently under the care of the hematology department and receiving maintenance chemotherapy. Lymphomas occurring in the oral cavity are uncommon and may exhibit non-specific clinical features that resemble benign oral and dental conditions. Therefore, a comprehensive clinical evaluation is necessary to achieve an early and accurate diagnosis, with histopathologic examination being essential for suspicious lesions.