Actinomycosis is a chronic suppurative disease primarily caused by Actinomyces israelii. Extra time may be necessary for diagnosis before the initiation of treatment, as some cases exhibit a tumor-like clinical presentation and others require differential diagnosis of unusual bacterial infections. Although biopsy is the most useful method to confirm the diagnosis, it is too invasive, particularly for young patients. Therefore, it is important to perform diagnostic imaging such as ultrasonography (US), computed tomography (CT), and magnetic resonance imaging (MRI), and we should know the specific findings of actinomycosis on each type of image.
We saw a case of actinomycosis with a hard, board-like mass in the temporal lesion and mastoiditis-like image findings. Actinomycosis is rare, so we should determine the specific infectious route and the image findings of actinomycosis on US and MRI.
