Primary diffuse large b-cell lymphoma of the lip: a case report and literature review.

Background: Primary diffuse large B-cell lymphoma (DLBCL) of the lip is a rare subtype of extranodal non-Hodgkin lymphoma that presents a diagnostic challenge due to its infrequent location and nonspecific clinical symptoms. The early suspicion of this diagnosis is often delayed because of its overlap with benign inflammation/infection, such as abscesses and mucoceles. Case presentation: This report describes a 65-year-old male with worsening swelling of the upper lip that was initially diagnosed as a maxillary space infection. Imaging studies, including ultrasound and MRI, showed a poorly defined mass, and an axial biopsy with immunohistochemistry confirmed a diagnosis of the germinal center B-cell (GCB) subtype of DLBCL. The patient was ultimately treated successfully with R-CHOP chemotherapy and achieved complete remission. Conclusion: This case illustrates both the importance of considering lymphoma in the differential diagnosis of a lip lesion that has persisted and requires ongoing clinical evaluation, as well as the benefit of multidisciplinary care for appropriate diagnosis and timely management.