[Case of cryptogenic organizing pneumonia with radiologically detectable lung cancer after disappearance of infiltrative shadows by steroid treatment].

An 82-year-old man with fever and a cough was admitted to hospital. A chest radiograph demonstrated infiltrative shadows in the bilateral middle and lower lung fields and a chest CT scan showed the shadows in the bilateral upper and lower lobes. After admission, infiltrative shadows in the right upper lobe increased and transbronchial lung biopsy (TBLB) specimens disclosed organizing exudates in the alveolar spaces. After steroid treatment, the radiographic infiltrates disappeared but the irregular shadows in the right lower lobe were still present. Lung adenocarcinoma was diagnosed by TBLB specimens of residual shadows. Few cases of cryptogenic organizing pneumonia (COP) with lung cancer have been reported, and further consideration should be given to the relationship between COP and lung cancer. We should consider that diagnostic preparations for chest radiographic imaging can lead to the recognition of several respiratory diseases.