Abstract
Actinomycosis is caused by Actinomyces israelli, an oral flora （oral indigenous bacteria）. Actinomycosis leads to nonspecific inflammation caused by suppurative bacteria and becomes chronic. Its typical symptoms include multiple abscesses, board-like induration, and severe trismus, which can become chronic. Moreover, pus, including drusen, discharges from an abscess. Here, we report two cases of atypical actinomycosis with a mass localized at the oral mucosa but without the typical clinical signs of actinomycosis. The first case was an 80-year-old male having an elastic hard mass on his lip. Excisional biopsy revealed sialadenitis with sulfur granules. The second case was a 59-year-old male having an elastic hard mass under the buccal mucosa. Puncture of the lesion revealed sulfur granules in pus. Thus, Actinomycosis with a localized nodule should be considered in the differential diagnosis of a neoplasm lesion and be accurately diagnosed before treatment.
