- Although rare, a high level of clinical suspicion is needed to diagnose and cure actinomycosis in patients with indolent, unresolving, or relapsing chronic inflammatory disease. - Actinomyces are commensals that become pathogenic when the mucosa is breached, and co-infection with other organisms is common. - Disease is defined by anatomical location; orocervicofacial disease is the most common, followed by thoracic and abdominopelvic disease. - A mass characteristically enlarges across tissue planes and local tissue invasion may lead to the formation of sinus tracts that can spontaneously heal and recur. - Actinomycosis often mimics other infections and malignancy—clinically and radiologically. - It is generally treated with long term antibiotics, usually penicillin, but surgery may be needed.