A case of actinomycosis arising in the cheek

We report a case of actinomycosis affecting the buccal mucosa in a patient with systemic lupus erythematosus. A 66-year-old woman with systemic lupus erythematosus presented with a swelling of the lower lip and left cheek. We suspected a salivary gland adenocarcinoma on inspection, palpation, and evaluation of the serum CA19-9 level. Enhanced computed tomography showed the location of the tumor. Other imaging techniques, including magnetic resonance imaging and ultrasonic tomography, were employed to support the clinical diagnosis. We performed a biopsy and histopathologically diagnosed the lesion as actinomycosis. The patient underwent abscess incision several times and received intravenous injections of 3g ABPC daily for 7 days, followed by 400mg of oral ABPC for 4 weeks. There was no sign of recurrence after treatment. Imaging methods were considered useful for the clinical diagnosis of actinomycosis.