Scalp actinomycosis mimicking soft tissue mass.

Actinomycosis is a rare, subacute or chronic bacterial infection, characterized by localized swelling with suppuration, abscess formation, tissue fibrosis, and draining sinuses. It is caused by gram-positive, pleomorphic non-spore-forming, non-acid-fast anaerobic or microaerophilic bacilli of the genus Actinomyces. In humans, actinomyces are often normally found in the oral cavity, the gastrointestinal tract and the female genital tract. Infections of the oral and cervicofacial regions are the most commonly reported cases. We present a case of subcutaneous actinomycosis, localized at the upper segment of the posterior neck space, with scalp involvement.