A Case of Peripheral Odontogenic Myxofibroma Arising in the Palatal Gingiva of the Maxillary Second Premolar Region: A Case Report

Odontogenic myxofibroma (OMF) is a rare benign mesenchymal odontogenic tumor characterized by myxoid stroma with a prominent fibrous component. Although it usually arises intraosseously within the jaws, the peripheral variant, peripheral odontogenic myxofibroma (POMF), which occurs in extraosseous soft tissues, is uncommon and may be clinically misdiagnosed as a reactive gingival lesion. We report a case of POMF in a 68-year-old man who was referred for evaluation of a painless, slowly enlarging swelling of the palatal gingiva in the left maxillary second premolar region, which had initially been diagnosed as chronic periodontitis at a local clinic. An intraoral examination revealed an elastic, firm mass with partial erythema on the palatal marginal gingiva. Panoramic radiography showed mild generalized horizontal bone loss without lesion-specific changes, and computed tomography revealed no bone resorption associated with the lesion. Exfoliative cytology was negative for intraepithelial lesions or malignancy. The lesion was excised with a 5-mm clinical margin, including periosteum, and superficial peripheral ostectomy of the adjacent cortical bone was performed. Histopathological examination revealed a myxoid stroma rich in mucinous matrix and collagen fibers, containing sparsely distributed spindle-shaped cells and scattered nests of odontogenic epithelium. Alcian blue staining revealed diffuse positivity, supporting the diagnosis of POMF. No recurrence was observed during a 2-year follow-up period. This case highlights a diagnostic pitfall in the tooth-bearing gingiva and underscores the importance of histopathological confirmation of persistent gingival masses. When imaging shows no apparent bone involvement, and clinical suspicion of malignancy is low, complete excision with an adequate soft-tissue margin and selective, limited bone removal may achieve local control while preserving the adjacent teeth; long-term follow-up remains advisable.