Primary Extra-nodal Diffuse Large B-cell Lymphoma of the Gingiva Mimicking a Dental Abscess: A Diagnostic Challenge.

Lymphomas are malignant proliferations of B or T lymphocytes, classified as Hodgkin or non-Hodgkin lymphomas. The malignant proliferation of lymphoid cells mainly occurs in lymph nodes, but in a small number of cases, it can be extranodal. The oral cavity represents a very rare primary extra-nodal location for non-Hodgkin lymphoma and can pose a diagnostic challenge for the dentist. We report the case of a woman in her 50s presenting a primary oral manifestation of a diffuse large B-cell lymphoma (DLBCL). The patient was complaining of an inflammatory swelling of the vestibular gingiva of the left maxillary premolars, which had been growing for four months. She had consulted several dentists who suspected a dental cause, without any clear argument in favor of a periodontal or endodontic etiology. Periodontal treatments were initiated, and multiple courses of antibiotics were prescribed without improvement in the clinical presentation. Finally, the patient was referred to the hospital where a biopsy of the gingival lesion was performed. Histological and immunohistochemical examinations led to the diagnosis of a DLBCL. The patient was referred to a hematology-oncology department and received polychemotherapy treatment until complete remission. Initial oral manifestations of lymphoma may mimic dental, endodontic, or periodontal pathology. Appropriate oral clinical and radiological examinations should exclude local causes. If these examinations are inconsistent with the clinical presentation, systemic diseases should be considered, and a prompt biopsy of the lesion should be performed to obtain a definitive diagnosis. Early detection of a primary oral lymphoma can improve the prognosis with timely multidisciplinary medical management.