Idiopathic Pulmonary Fibrosis: Current Concepts Jay H. Ryu, M.D., Thomas V. Colby, M.D., Thomas E. Hartman, M.D.  Mayo Clinic Proceedings  Volume 73, Issue 11, Pages 1085-1101 (November 1998) DOI: 10.4065/73.11.1085 Copyright © 1998 Mayo Foundation for Medical Education and Research Terms and Conditions

Fig. 1 Relationships among usual interstitial pneumonia, idiopathic interstitial pneumonias in general, clinically diagnosed idiopathic pulmonary fibrosis (IPF), and interstitial lung diseases. Usual interstitial pneumonia is the most common histologic pattern in cases previously defined as IPF. Mayo Clinic Proceedings 1998 73, 1085-1101DOI: (10.4065/73.11.1085) Copyright © 1998 Mayo Foundation for Medical Education and Research Terms and Conditions

Fig. 2 Chest radiograph of 73-year-old man with usual interstitial pneumonia. Coarse reticular infiltrates with associated honeycombing are seen in periphery of lungs and lung bases. Mayo Clinic Proceedings 1998 73, 1085-1101DOI: (10.4065/73.11.1085) Copyright © 1998 Mayo Foundation for Medical Education and Research Terms and Conditions

Fig. 3 Historical view of histopathologic lesions included in category of idiopathic pulmonary fibrosis (IPF). During past 15 years, several clinicopathologic entities have been separated from IPF based on differences in histologic features, clinical course, response to therapy, and prognosis. AIP = acute interstitial pneumonia; BOOP = bronchiolitis obliterans organizing pneumonia; DIP = desquamative interstitial pneumonia; NSIP = nonspecific interstitial pneumonia; RB-ILD = respiratory bronchiolitis-associated interstitial lung disease; UIP = usual interstitial pneumonia. Mayo Clinic Proceedings 1998 73, 1085-1101DOI: (10.4065/73.11.1085) Copyright © 1998 Mayo Foundation for Medical Education and Research Terms and Conditions

Fig. 4 Histopathology of usual interstitial pneumonia. A, Scanning power microscopy shows patchy fibrosing process with severe scarring in pleural and subpleural regions. Some of adjacent lung tissue is entirely normal (lower portion of field). B, At junction of fibrotic lung and normal lung, higher power shows active fibroblastic proliferation as more lung is affected by fibrotic process. Fibroblastic focus is illustrated as a parallel fascicle of fibroblasts at approximately 7 o'clock. For corresponding high-resolution computed tomographic findings of usual interstitial pneumonia, see Figure 8. Mayo Clinic Proceedings 1998 73, 1085-1101DOI: (10.4065/73.11.1085) Copyright © 1998 Mayo Foundation for Medical Education and Research Terms and Conditions

Fig. 5 Histopathology of desquamative interstitial pneumonia. A, Scanning power microscopy shows a uniform diffuse process without subpleural accentuation seen in usual interstitial pneumonia. Occasional bluish reactive lymphoid follicles are present. B, Higher power shows slight alveolar septal thickening and marked accumulation of macrophages in airspaces. A few macrophages are multinucleated. For corresponding high-resolution computed tomographic findings of desquamative interstitial pneumonia, see Figure 9. Mayo Clinic Proceedings 1998 73, 1085-1101DOI: (10.4065/73.11.1085) Copyright © 1998 Mayo Foundation for Medical Education and Research Terms and Conditions

Fig. 6 Histopathology of bronchiolitis obliterans organizing pneumonia. A, Scanning power microscopy shows periphery of wedge biopsy with relative preservation of lung architecture. In central portions of biopsy specimen, bluish tufts of fibroblastic tissue are evident. B, Higher power shows these tufts of fibroblastic tissue to be present within airspaces, with intervening alveolar walls showing only slight thickening, inflammation, and type II cell metaplasia. For corresponding high-resolution computed tomographic findings of bronchiolitis obliterans organizing pneumonia, see Figure 10. Mayo Clinic Proceedings 1998 73, 1085-1101DOI: (10.4065/73.11.1085) Copyright © 1998 Mayo Foundation for Medical Education and Research Terms and Conditions

Fig. 7 Histopathology of nonspecific interstitial pneumonia. A, Scanning power microscopy shows patchy process with interstitial widening but without marked subpleural fibrosis or honeycomb change as seen in usual interstitial pneumonia and without airspace organization as seen in bronchiolitis obliterans organizing pneumonia. B, Higher power shows patchy alveolar septal thickening and chronic inflammatory infiltrate. For corresponding high-resolution computed tomographic findings of nonspecific interstitial pneumonia, see Figure 11. Mayo Clinic Proceedings 1998 73, 1085-1101DOI: (10.4065/73.11.1085) Copyright © 1998 Mayo Foundation for Medical Education and Research Terms and Conditions

Fig. 8 High-resolution computed tomogram at level of right middle lobe bronchus in 72-year-old man with usual interstitial pneumonia, demonstrating extensive subpleural honeycombing. Associated subpleural reticular opacities are evident. Traction bronchiectasis can also be seen involving posterior segmental branches of right middle lobe and superior segmental branches of right lower lobe. Mayo Clinic Proceedings 1998 73, 1085-1101DOI: (10.4065/73.11.1085) Copyright © 1998 Mayo Foundation for Medical Education and Research Terms and Conditions

Fig. 9 High-resolution computed tomogram of 59-year-old man with desquamative interstitial pneumonia, showing bilateral areas of ground-glass attenuation. A few irregular linear opacities are seen in subpleural lung bilaterally. No honeycombing was identified. Mayo Clinic Proceedings 1998 73, 1085-1101DOI: (10.4065/73.11.1085) Copyright © 1998 Mayo Foundation for Medical Education and Research Terms and Conditions

Fig. 10 High-resolution computed tomogram of 70-year-old man with bronchiolitis obliterans organizing pneumonia, showing subpleural areas of consolidation bilaterally. Mayo Clinic Proceedings 1998 73, 1085-1101DOI: (10.4065/73.11.1085) Copyright © 1998 Mayo Foundation for Medical Education and Research Terms and Conditions

Fig. 11 High-resolution computed tomogram of 56-year-old man with nonspecific interstitial pneumonia, showing bilateral areas of ground-glass attenuation most marked in right lower lobe medially. Mayo Clinic Proceedings 1998 73, 1085-1101DOI: (10.4065/73.11.1085) Copyright © 1998 Mayo Foundation for Medical Education and Research Terms and Conditions