Bronchiolitis obliterans following allogeneic bone marrow transplantation

Photomicrographs of a partially obliterated bronchiole in a patient who has received an allogeneic bone marrow transplant. Left: Hematoxylin and eosin stained section shows a largely obliterated bronchiole with peribronchiolar fibrosis and an associated infiltrate of mononuclear inflammatory cells. Right: An elastic tissue stain outlines the elastic layer of the same bronchiole pictured on the left and shows a compressed but patent lumen (arrow).