Honeycomb-like structures in sarcoidosis pathologically showing granulomas in walls of clustered bronchioles.

In the clinical setting, it is often difficult to judge whether honeycomb-like structures represent progression of fibrosis in pulmonary sarcoidosis or a complication by interstitial pneumonitis. This report described a valuable case in which pathology of video-assisted thoracoscopic surgery specimens collected from the lungs with honeycomb-like structures that were continuous with the dilated bronchioles on chest computed tomography (CT) showed granulomas in the membranous bronchiole walls, thereby demonstrating that the honeycomb-like structures were lung lesions of sarcoidosis. Pathological features of these structures on chest CT included cystic changes attributable to incorporation of peripheral alveoli into dilated bronchioles in lobules: these findings in lung sarcoidosis were different from those corresponding to honeycomb lung in idiopathic pulmonary fibrosis/usual interstitial pneumonia. Radiological and pathological findings showed the possibility that progressive clustering of dilated bronchi and bronchioles causes cystic changes, resulting in the formation of honeycomb-like structures as fibrosis progresses in sarcoidosis with lung involvement.