• Also known as "cryptogenic organizing pneumonia" in the British literature, this disease is characterized by granulation tissue plugs (i.e., Masson bodies) within the lumen of small airways and extending into alveolar ducts and alveoli. Masson bodies are rounded balls of myxomatous (bluish) connective tissue that form intraluminal polyps within bronchioles and air spaces

• The diagnosis of idiopathic BOOP should only be made after careful consideration of clinical and radiological features since the histologic picture of BOOP can be seen in several conditions e.g., pulmonary infections, organizing DAD, bronchial obstruction, aspiration pneumonia, hypersensitivity pneumonitis, drug reaction, toxic fumes, and bone marrow, lung and heart-lung transplantation

BOOP
H&E
Tricurome