Airway Diseases

Lymphocytic bronchiolitis

Viral infections, acute rejection of the lung, and acute graft versus host disease may have peribronchiolar infiltrates of lymphocytes and plasma cells. This is a potentially reversible lesion.

Follicular bronchiolitis

A more chronic type of bronchitis has lymphoid follicles with many B lymphocytes surrounding small airways. Associated diseases include collagen-vascular diseases, immunodeficiency diseases, and hypersensitivity reactions. The irregularly-shaped bronchiole is to the right and the artery to the left. The ill-defined nodule of lymphoid tissue between them contains scattered larger histiocytes.

Diffuse panbronchiolitis is characterized by a peribronchiolar lymphoid infiltrate with foamy macrophages around respiratory bronchioles.

Proliferative bronchiolitis

A proliferative bronchiolitis with active granulation tissue that involves only the bronchiolar lumen, shown here, may be seen in collagen vascular diseases, reactions to toxic gases or smoke, and aspiration of gastric acid. Proliferative bronchiolitis does not involve alveolar spaces as does COP (BOOP).

Cicatricial, constrictive bronchiolitis obliterans

This lesion, found in lung transplant rejection and graft versus host disease, consists of collagenous scar eccentrically narrowing the lumen of bronchioles (arrow). Here, the airway smooth muscle can be seen around the scar. Note also that there are a number of hemosiderin-filled (brown macrophages) in alveolar spaces. These are a common finding in transplanted lungs.

Cicatricial, constrictive bronchiolitis obliterans

An elastic van Gieson stain shows the subepithelial deposition of fibrous tissue (pink) between the epithelial basement membrane and the black elastic layer (arrows). Smooth muscle (SM) is hypertrophied. Note that the process is focal. The epithelium shows focal erosions.

See also Case 11

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