[A case of nonspecific interstitial pneumonia with reversed halo sign on chest HRCT].

A 39-year-old man was referred to our hospital with anterior chest discomfort, dry cough and shortness of breath. His blood test revealed mild inflammatory change and high serum KL-6 levels. Chest radiograph and computed tomography (CT) showed ground glass attenuation with volume loss in both lower lung fields, and in particular a reversed halo sign was shown on high-resolution CT (HRCT). As transbronchial lung biopsy and bronchoalveolar lavage did not enable a diagnosis, video-assisted thoracic surgery was performed. The histological findings of the resected specimen showed cellular nonspecific interstitial pneumonia. This suggested the possibility of collagen vascular disorder (CVD) associated with interstitial pneumonitis, but no criteria of CVD were fulfilled. Although the reversed halo sign is relatively specific for cryptogenic organizing pneumonia, we report a case of cellular nonspecific interstitial pneumonia showing this sign on chest HRCT.