Cryptogenic Organizing Pneumonia (Bronchiolitis Obliterans Organizing Pneumonia) By Joyce Lee, MD, MAS, University of Colorado School of Medicine Reviewed / Revised Jun 2021 | Modified Sep 2022 View Patient Education Diagnosis Treatment Topic Resources Cryptogenic Organizing Pneumonia Cryptogenic organizing pneumonia is an idiopathic condition in which granulation tissue obstructs alveolar ducts and alveolar spaces with chronic inflammation occurring in adjacent alveoli.