Primary cutaneous actinomycosis.

Actinomycosis is a chronic, progressive, suppurative infection, prevalent over the neck, thorax or abdomen. As it rarely occurs with few clinical symptoms, its diagnosis requires a high index of clinical suspicion. We report a case of primary cutaneous actinomycosis affecting the back. The patient was treated with benzyl penicillin and sulfonamides and showed no recurrence at 1 year follow-up.