[Urachal Actinomycosis : A Case Report].

The patient was a 66-year-old woman who was examined by a local physician for the chief complaint of a mass palpable in the left lower abdomen. Abdominal plain computed tomography (CT) indicated a subcutaneous mass extending continuously from the apex of the bladder to the retropubic space, and she was referred to our medical department. Tumor markers were normal, and cystoscopic examination indicated no clear findings. Abdominal contrast-enhanced CT and plain abdominal magnetic resonance imaging results led to suspicion of actinomycosis. An open biopsy was performed on the subcutaneous mass, and subsequent histopathological testing led to a definitive diagnosis of actinomycosis. After 2 weeks of antibiotic therapy, the mass had diminished on CT. There has been no relapse approximately 24 weeks after discontinuation of the antibiotic therapy.