High-Grade B-Cell Lymphoma of the Right Maxillary Sinus: A Case Report

High-grade B-cell lymphoma (HGBCL) is a rare, aggressive cancer whose presentation in the maxilla is exceptionally uncommon and often mimics odontogenic disease.A 62-year-old female presented with an eight-month history of right maxillary swelling.Clinical examination revealed a firm vestibular mass from tooth 1.4 to 1.6, facial asymmetry, and loss of the nasolabial fold.Cone beam CT showed an ill-defined osteolytic lesion destroying the maxillary sinus walls and infraorbital canal, featuring periodontal ligament widening, root resorption, and a large soft tissue mass.Biopsy revealed sheets of atypical lymphoid cells.Immunohistochemistry was positive for CD20, PAX5, and BCL6.Fluorescence in situ hybridization confirmed MYC and BCL2 rearrangements, diagnosing HGBCL with these rearrangements (HGBCL-R).The patient was referred and started on R-CHOP chemotherapy.The case highlights that persistent unilateral swelling, unexplained dental findings like root resorption, and lesions unresponsive to treatment should raise suspicion for malignancy.Dental practitioners are critical for early recognition, and increased awareness can improve outcomes for this aggressive lymphoma.