[A case of Farmer's lung accompaign with caseous granuloma, monitored with serum KL-6 and SP-D].

A 65-year-old man was admitted to our hospital with a productive cough, fever, and dyspnea; his chest radiographs revealed diffuse nodular and ground-glass opacities. He had worked on a farm for 11 years. Six months earlier, he had presented with similar symptoms at another hospital, and was admitted with suspected atypical pneumonia. After treatment with antibiotics, his condition improved and he was discharged. Examination on admission to our hospital revealed markedly elevated serum KL-6 levels. Histological findings from specimens obtained by video-assisted thoracic surgical lung biopsy showed caseating and non-caseating epitheloid cell granuloma, lymphocyte infiltration, and alveolitis. Bacteriological tests for mycobacteria and fungi were all negative. Farmer's lung was diagnosed in accordance with the criteria for hypersensitive pneumonia. It is generally accepted that the distinguishing histological finding for Farmer's lung disease is non-caseating epitheloid cell granuloma, but in this case, caseous granuloma was also present.