BOOP stands for Bronchiolitis obliterans organizing pneumonia.
It is a lung disease that causes inflammation in the small air tubes (bronchioles) and air sacs (alveoli).
It can be caused by viruses, various drugs, and other medical conditions. In many cases, the underlying cause of BOOP is unknown.
BOOP is characterized by granulation tissue in the bronchiolar lumen, alveolar ducts, and some alveoli, associated with a variable degree of interstitial and airspace infiltration by mononuclear cells and foamy macrophages.
BOOP is differentiated from organizing pneumonia, which is defined by the presence of granulation tissue in the distal air spaces. But when associated with granulation tissue in the bronchiolar lumen, organizing pneumonia is qualified by the term bronchiolitis obliterans (BO). Hence the term "bronchiolitis obliterans organizing pneumonia" is used.
Some medical practices submit the ICD-10 code J84.116 in claims when documentation describes BOOP perfectly.