Organizing pneumonia is a common nonspecific histologic pattern seen in a wide variety of settings, including infection, granulomatous disease, vasculitis, hemorrhage, eosinophilic pneumonia, drug-induced lung injury, and many others. Pathologically, it is characterized by intraluminal polypoid plugs of granulation tissue extending continuously from the distal air spaces into alveolar ducts and alveoli. Other features include chronic inflammation of the walls of surrounding alveoli, increased foamy macrophages, and preserved lung architecture. When these features are the predominant pathologic findings and there is no other histology suggestive of another process, a pathologic diagnosis of organizing pneumonia is made.1 Clinically cough is most common; dyspnea if present is mild. Radiographs typically show bibasilar, patchy alveolar infiltrates with a peripheral distribution. Although the classification of this syndrome remains controversial, the nomenclature used here is based on the American Thoracic Society/European Respiratory Society consensus statement on idiopathic interstitial pneumonia published in 2002.1 The term COP is used when these clinical, radiographic, and pathologic findings are idiopathic, and BOOP is used when it is associated with other entities such as radiation or connective tissue diseases.