Regular resident becomes aggressive enemy: Diagnosed on cytology.

Actinomycosis, an oral cavity commensal, causes cervicofacial infection in patients associated with an immunosuppression state and local mucosal injuries. Bone involvement by this commensal is rare. In the present case, we report a case of left peri mandibular soft tissue, soft to firm, tender swelling in a 39-year-old immunocompetent male diagnosed as Actinomycosis infection on fine needle aspiration cytology (FNAC) and cell block preparation.