Oral Focal Mucinosis Occurring in the Palate: A Case Report

Oral focal mucinosis (OFM) is a rare disease characterized by the localized accumulation of mucin within the oral connective tissue, which is thought to result from excessive production of hyaluronic acid by fibroblasts.Because its clinical features are non-specific, a preoperative diagnosis is often difficult.Herein, we report a case of OFM arising in the hard palate.A 38-year-old man was referred to our department with an asymptomatic, elastic, firm mass measuring 15 × 15 mm in the left hard palate.Computed tomography showed no evidence of bone resorption, whereas magnetic resonance imaging demonstrated a well-defined, contrast-enhancing lesion with low signal intensity on T1-weighted images and high signal intensity on T2weighted images.A benign salivary gland tumor was clinically suspected, and an incisional biopsy was performed.Histopathological examination revealed a well-demarcated, non-encapsulated myxoid lesion composed of fibroblasts in an Alcian blue-positive myxoid matrix.Immunohistochemical staining was negative for S-100 protein, CD34, and α-SMA, confirming the diagnosis of OFM.The lesion was completely excised under general anesthesia, and no recurrence was observed during a 24-month follow-up period.