[Three cases of pulmonary actinomycosis]

Three cases of pulmonary actinomycosis are reported. Case 1 was a 33-year-old man complaining of hemosputum. A large mass lesion was noted in the right upper lobe and surgically resected. Actinomycosis was diagnosed pathologically. The second case was a 41-year-old man with lung abscess. An actinomyces species was cultured by percutaneous aspiration biopsy. He was effectively treated with clindamycin. The third case was a 46-year-old man with a chronic cough and cavitary lesion. Gram staining of sputum revealed sulfur granules. Piperacillin was administered with prompt response. All three cases had dental disease and two had diabetes mellitus. In patients with a mass lesion or those with lung abscess not effectively treated by cephem antibiotics, actinomycosis should be suspected especially when diabetes mellitus and/or dental disease coexists. Adequate treatment may not always require long-term antibiotics.