Figure 2
From: Hypersensitivity pneumonitis: lessons for diagnosis and treatment of a rare entity in children
The 3 typical findings of HP are 1. bronchiolitis, 2. alveolitis and 3. loosely formed non-caseating histiocytic granulomas. (A) shows bronchiolitis (B) with lymph follicles (L) and increased amounts of lymphocytes in the walls of the bronchiole and alveolitis (+). Figure 2(B) depicts a typical granuloma (arrows) with multinucleated histiocytic giant cells (*). Immune histochemical stains for CD 3 confirm the presence of increased amounts of T cells in the alveoli (asterix) and septi (arrow) (C), and stains CD68 the presence of macrophages in the alveoli (asterisk) (D). (E) demonstrates intraepithelial T lymphocytes in the bronchial epithelium and (F) aggregates of B lymphocytes (lymph follicles). Single scattered B lymphocytes were also found in alveolar septa and alveoli. Magnification is indicated by bar in each figure.