Primary actinomycosis of an extremity: a case report and review.

Primary infection of an extremity is an uncommon feature of actinomycosis and can readily be confused with actinomycetoma caused by aerobic actinomycetes such as Nocardia and Streptomyces. A case of primary actinomycosis of the leg is reported, and 35 cases published in the English-language literature are reviewed. There were 14 cases of upper extremity infections and 22 cases of lower extremity infections. Antecedent trauma had occurred in 21 cases. Lesions began in the skin, subcutaneous tissue, muscle, bone, and joint space. Spread to contiguous structures was characteristic, and most lesions eventually involved all of the aforementioned structures. The lesions were typical of actinomycosis with sinus formation and granules in the pus. Cultures were positive in 17 cases. Surgical therapy was necessary in most instances; penicillin remains the drug of choice. Pending results of culturing, a lesion with granules of branching gram-positive bacteria would best be treated empirically with penicillin and a sulfonamide. Prognosis is excellent.