Actinomycosis of the common bile duct presenting as chronic cholecystitis

Actinomycosis of the common bile duct can masquerade as cholecystitis. This is the first report of a case. The bacteriologic and pathologic characteristics are described. This opportunistic saprophytic organism took advantage of 15 years of prednisone therapy for rheumatoid arthritis. The actinomycosis was successfully treated with tetracycline-deoxycycline for 6 weeks.