Bronchiolitis, perivascular inflammation, and peribronchitis characterize human pulmonary GVHD. (A-D) Representative images of human pulmonary GVHD. Upper images are H&E stained, and lower figures are EVG stained. (A) BO, (B) PPFE, (C) peribronchitis and cholesterol cleft, and (D) perivascular inflammation. (E) Numbers of patients who had BO, PPFE, peribronchitis, and organizing pneumonia (OP), with overlap among the patients shown. (F-J) Images of specimens stained with H&E (F) or immunohistochemically stained for CD4 (G), CD8 (H), CD20 (I), and CD68 (J) in bronchiolitis.