Idiopathic BOOP
Post infection BOOP
Drug or medication BOOP
Focal nodular BOOP
Rheumatological or connective tissue BOOP
Bone marrow transplantation BOOP
Lung transplantation BOOP
AIDS or HIV infection BOOP
Radiation therapy BOOP
Cancer and lymphoma-related BOOP
Seasonal BOOP
Inflammatory bowel disease BOOP
Tryptophan-related BOOP
Textile printing dye BOOP

Focal nodular BOOP

Sometimes, the chest x-ray shows BOOP as a single rounded shadow. It has the appearance of a lung cancer. Because of this, the lesion is removed surgically. For the most part, these will not recur again.

In rare situations, this single lesion represents the beginning of typical 'idiopathic' BOOP. Prednisone therapy will then result in complete resolution.