抄録
We report a rare case of actinomycosis in the upper lip mucosa. A 50-year-old woman complained of swelling on the inner surface of the right upper lip. A mass lesion 10 mm in diameter was found on the mucosal surface of the right upper lip. The clinical diagnosis was a benign tumor or cystic disease and the lesion was surgically resected. Histopathologically, the lesion mainly comprised chronic granulation tissue with prominent neutrophil infiltration and actinomycotic sulfur granules. The lesion was finally diagnosed as actinomycosis. The postoperative course was uneventful and no postoperative recurrence has been identified.