[A case of pulmonary sarcoidosis demonstrating panlobular ground-glass opacity with mosaic distribution].

A 68-year-old woman presenting dyspnea on exertion was admitted. Hypoxemia and a considerably elevated level of serum KL-6 were noted. Chest high-resolution computed tomography (HRCT) scans demonstrated panlobular ground-glass opacities with a mosaic distribution and hilar and mediastinal lymphadenopathy. Bronchoalveolar lavage revealed an increased percentage of lymphocytes and an elevated CD4/CD8 ratio, implicating a diagnosis of sarcoidosis. However, as we could not exclude other diffuse lung diseases because of unusual HRCT pattern in sarcoidosis, video-assisted thoracoscopic lung biopsy was performed. The histology of epithelioid cell granulomas in the specimens of the lung and the lymph nodes confirmed a diagnosis of sarcoidosis. The lung specimens corresponding to areas of increased opacity demonstrated diffuse alveolitis with minimal fibrosis between individual granulomas. Immunohistochemistry for KL-6 provided positive results on alveolar lining cells in areas of alveolitis but not on granulomas. After steroid treatment, the ground-glass opacities disappeared and the serum KL-6 level normalized. We discuss this rare case of pulmonary sarcoidosis presenting panlobular ground-glass opacities with mosaic distribution.