American Thoracic Society Quick-Reference GUIDELINES Apps
Issue link: https://eguideline.guidelinecentral.com/i/1346795
19 Table 6. Histopathological Criteria for the Diagnosis of HP (Other than "Hot-Tub Lung" a ) footnotes a Histological findings in hot-tub lung are distinctly different from nonfibrotic and fibrotic forms of classic HP. b Granulomas in HP are smaller, less tightly clustered, and lack the perigranulomatous hyaline fibrosis commonly seen in sarcoidosis. c Fibrotic HP may show classic features of nonfibrotic HP (cellular HP) in less fibrotic or nonfibrotic areas; if present, this combination of findings is a histological clue to the diagnosis of HP. d Updates to the classification of IIPs by Travis and colleagues and diagnostic guidelines for idiopathic pulmonary fibrosis tightly link a UIP pattern with idiopathic pulmonary fibrosis and an NSIP pattern with idiopathic NSIP. e Bridging fibrosis spans subpleural and centriacinar or neighboring centriacinar fibrotic foci. Figure 3. Surgical Lung biopsy Specimen from a Patient with Nonfibrotic Hypersensitivity Pneumonitis (HP) (A) Low-magnification photomicrograph showing preservation of lung architecture and a cellular chronic interstitial pneumonia that is accentuated around bronchioles (asterisks). Magnification, 20×. (B) Higher-magnification photomicrograph showing expansion of distal acinar and peribronchiolar interstitium by a cellular infiltrate of mononuclear inflammatory cells. Magnification, 88×. (C) Photomicrograph showing a cellular bronchiolitis in which the peribronchiolar interstitium is expanded by cellular infiltrate, predominantly comprising lymphocytes without lymphoid aggregates or follicles. Magnification, 108×. (D) Higher-magnification view of airway illustrated in C, demonstrating a poorly formed nonecrotizing granuloma (arrow) characteristic of HP comprising loose clusters of epithelioid cells (macrophages). Magnification, 400×. (E) High-magnification photomicrograph illustrating another poorly formed non-necrotizing granuloma (arrows) in the same biopsy specimen from a patient with nonfibrotic HP. Magnification, 264×. Hematoxylin and eosin staining was used.