Non-Hodgkin lymphoma (NHL) comprises a heterogeneous group of lymphoid malignancies with clinical behaviour ranging from indolent to highly aggressive. These neoplasms arise from lymphoid cells at different stages of differentiation, and their biological characteristics reflect their cellular origin. Intraoral NHL is uncommon and may involve either the jaw bones or the soft tissues of the oral cavity. We report the case of a 54-year-old man who presented with persistent buccal space swelling following extraction of the mandibular right second molar (tooth 47) for presumed odontogenic infection. Despite antibiotic therapy, the swelling progressively increased in size and was associated with the development of lower-lip paresthesia. An initial clinical diagnosis of antibioma was made; however, the persistence and progression of the lesion prompted further investigation. Histopathological examination and immunohistochemical analysis established a diagnosis of diffuse large B-cell lymphoma (DLBCL). This case highlights the importance of considering malignant disease in the differential diagnosis of persistent or progressive orofacial swellings, particularly when presumed odontogenic lesions fail to respond to appropriate treatment or are accompanied by neurosensory disturbances.