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.