As do other anaerobic infections, actinomycosis thrives in the presence of necrotic tissues and foreign bodies and frequently participates in polymicrobial infections. A fourth category is pelvic actinomycosis, which appears in women who use IUDs. The disease may also present with widespread hematogenous dissemination to multiple organ systems. Wherever the site of infection, actinomycosis characteristically produces chronic granulomatous inflammation that burrows deeply through contiguous tissues without respect to fascial planes. Consequently, draining sinus tracts are often present and may be purulent or sanguineous.
Actinomycosis usually pursues an indolent but progressive course.
The initial symptom is often a firm, indurated swelling in the region of the mandible, and a tumor or cold abscess is often suspected clinically. On occasion, pain, inflammation, and fever are more prominent, and the disease may mimic a pyogenic infection. Sinus tracts may be involved in long-standing disease. Soft tissue infection is more common than bone involvement. Because actinomycosis spreads without regard for tissue planes, infection of regional nodes is not a characteristic feature, although it can occur.