absent or unrecognized. Digital clubbing may be seen in advanced Þbrotic HP.

CT Findings

The radiologic Þndings of chronic HP are characterized by the presence of Þbrosis, although evidence of active disease is often present. TSCT Þndings of chronic HP include intralobular interstitial thickening, irregular interlobular septal thickening, traction bronchiectasis, and HC superimposed on Þndings of subacute HP such as bilateral patchy areas of GGO, poorly deÞned small centrilobular nodules, and lobular areas of mosaic attenuation on inspiratory images and of air trapping on expiratory CT images [30]. Chronic HP may closely mimic UIP and Þbrotic NSIP. The TSCT features that best differentiated chronic HP from UIP and NSIP are the presence of lobular areas of mosaic attenuation and centrilobular small nodules and the lack of lower zone predominance of HC [22].

CT–Pathology Comparisons

Histologic features of chronic HP comprise overlapping UIP-like pattern, a NSIP-like pattern, organizing pneumonia pattern, centrilobular Þbrosis, or bridging Þbrosis (continuous Þbrosis between the centrilobular and subpleural location) with or without granuloma [31].

Patient Prognosis

Avoidance of further exposure to potential antigen is crucial in the management. Corticosteroids can be tried, but patients with chronic HP often progress to irreversible pulmonary Þbrosis and about 30 % of them die within a few years of diagnosis. In general, the risk of mortality increases with evidence of Þbrosis in lung biopsy or TSCT or with a more severe respiratory impairment on pulmonary function tests [32].

End-stage Fibrotic Pulmonary Sarcoidosis

Pathology and Pathogenesis

present in the disease, often accompanied by a variety of distinctive cytoplasmic inclusions (e.g., Schaumann bodies, asteroid bodies). Spontaneous resolution is common, suggesting that the granulomas often resolve but in other patients healing is by Þbrosis, often with HC [33].

Symptoms and Signs

Patients with end-stage Þbrocystic pulmonary sarcoidosis commonly show varying degree of severe restrictive and obstructive pulmonary functional impairment. They complain of marked dyspnea and signs of right heart failure, especially lower extremity edema.

CT Findings

TSCT Þndings of end-stage Þbrotic pulmonary sarcoidosis include reticular opacity, traction bronchiectasis, architectural distortion, Þbrotic cysts, bullae, and paracicatricial emphysema [34]. Occasionally, HC-like cysts are seen, which are most commonly distributed in the subpleural regions of the middle and upper lung zones, whereas the lung bases are usually spared [24]. Distribution and location of Þbrosis and HC-like cysts are the differential diagnostic points from UIP.

CT–Pathology Comparisons

Obstruction of lobar or segmental bronchi by either wall Þbrosis or accumulation of granulomas may result in parenchymal distortion and cyst formation.

Patient Prognosis

End-stage pulmonary sarcoidosis with cor pulmonale may warrant supplemental oxygen, diuretics, and bronchodilators for airway obstruction. Lung transplantation has been performed successfully [35].

References

The characteristic histopathologic lesion of pulmonary sarcoidosis is the non-necrotizing granuloma, typically occurring within areas of sclerotic Þbrosis. In sarcoidosis, small granulomas have a tendency to coalesce to form larger nodular lesions, all embedded in refractile eosinophilic collagen. Granulomas are distributed along lymphatic routes in the pleura, within the intralobular septa, and along the bronchovascular bundles. Multinucleate giant cells are characteristically

1.Arakawa H, Honma K. Honeycomb lung: history and current concepts. AJR Am J Roentgenol. 2011;196:773Ð82.

2.American Thoracic Society, European Respiratory Society. American Thoracic Society/European Respiratory Society International Multidisciplinary Consensus ClassiÞcation of the Idiopathic Interstitial Pneumonias. This joint statement of the American Thoracic Society (ATS), and the European Respiratory

Society (ERS) was adopted by the ATS board of directors, June 2001 and by the ERS Executive Committee, June 2001. Am J Respir Crit Care Med. 2002;165:277Ð304.

3.Akira M, Sakatani M, Ueda E. Idiopathic pulmonary Þbrosis: progression of honeycombing at thin-section CT. Radiology. 1993;189:

687Ð91.

4. Watadani T, Sakai F, Johkoh T, et al. Interobserver variability in the CT assessment of honeycombing in the lungs. Radiology. 2013;266: 936Ð44.

5. Kligerman SJ, Groshong S, Brown KK, Lynch DA. NonspeciÞc interstitial pneumonia: radiologic, clinical, and pathologic considerations. Radiographics. 2009;29:73Ð87.

6. Akira M, Yamamoto S, Inoue Y, Sakatani M. High-resolution CT of asbestosis and idiopathic pulmonary Þbrosis. AJR Am J Roentgenol. 2003;181:163Ð9.

7. Silva CI, Muller NL, Hansell DM, Lee KS, Nicholson AG, Wells AU. NonspeciÞc interstitial pneumonia and idiopathic pulmonary Þbrosis: changes in pattern and distribution of disease over time. Radiology. 2008;247:251Ð9.

8. Flaherty KR, Toews GB, Travis WD, et al. Clinical signiÞcance of histological classiÞcation of idiopathic interstitial pneumonia. Eur Respir J. 2002;19:275Ð83.

9. Lee HY, Lee KS, Jeong YJ, et al. High-resolution CT Þndings in Þbrotic idiopathic interstitial pneumonias with little honeycombing: serial changes and prognostic implications. AJR Am J Roentgenol. 2012;199:982Ð9.

10.Shin KM, Lee KS, Chung MP, et al. Prognostic determinants among clinical, thin-section CT, and histopathologic Þndings for Þbrotic idiopathic interstitial pneumonias: tertiary hospital study. Radiology. 2008;249:328Ð37.

11.Akira M, Inoue Y, Kitaichi M, Yamamoto S, Arai T, Toyokawa K. Usual interstitial pneumonia and nonspeciÞc interstitial pneumonia with and without concurrent emphysema: thin-section CT Þndings. Radiology. 2009;251:271Ð9.

12.Cottin V, Nunes H, Brillet PY, et al. Combined pulmonary Þbrosis and emphysema: a distinct underrecognised entity. Eur Respir J. 2005; 26:586Ð93.

13.Raghu G, Collard HR, Egan JJ, et al. An ofÞcial ATS/ERS/JRS/ ALAT statement: idiopathic pulmonary Þbrosis: evidence-based guidelines for diagnosis and management. Am J Respir Crit Care Med. 2011;183:788Ð824.

14.King Jr TE, Pardo A, Selman M. Idiopathic pulmonary Þbrosis. Lancet. 2011;378:1949Ð61.

15.Muller NL, Coiby TV. Idiopathic interstitial pneumonias: highresolution CT and histologic Þndings. Radiographics. 1997;17: 1016Ð22.

16.Travis WD, Hunninghake G, King Jr TE, et al. Idiopathic nonspeciÞc interstitial pneumonia: report of an American Thoracic Society project. Am J Respir Crit Care Med. 2008;177:1338Ð47.

17.Katzenstein AL, Myers JL. NonspeciÞc interstitial pneumonia and the other idiopathic interstitial pneumonias: classiÞcation and diagnostic criteria. Am J Surg Pathol. 2000;24:1Ð3.

18.Kim TS, Lee KS, Chung MP, et al. NonspeciÞc interstitial pneumonia with Þbrosis: high-resolution CT and pathologic Þndings. AJR Am J Roentgenol. 1998;171:1645Ð50.

19.Roggli VL, Gibbs AR, Attanoos R, et al. Pathology of asbestosisan update of the diagnostic criteria: report of the asbestosis committee

of the college of American pathologists and pulmonary pathology society. Arch Pathol Lab Med. 2010;134:462Ð80.

20.Akira M, Yamamoto S, Yokoyama K, et al. Asbestosis: highresolution CT-pathologic correlation. Radiology. 1990;176: 389Ð94.

21.Nishiyama O, Taniguchi H, Kondoh Y, et al. Familial idiopathic pulmonary Þbrosis: serial high-resolution computed tomography Þndings in 9 patients. J Comput Assist Tomogr. 2004;28:443Ð8.

22.Silva CI, Muller NL, Lynch DA, et al. Chronic hypersensitivity pneumonitis: differentiation from idiopathic pulmonary Þbrosis and nonspeciÞc interstitial pneumonia by using thin-section CT. Radiology. 2008;246:288Ð97.

23.Nunes H, Uzunhan Y, Gille T, Lamberto C, Valeyre D, Brillet PY. Imaging of sarcoidosis of the airways and lung parenchyma and correlation with lung function. Eur Respir J. 2012;40:750Ð65.

24.Abehsera M, Valeyre D, Grenier P, Jaillet H, Battesti JP, Brauner MW. Sarcoidosis with pulmonary Þbrosis: CT patterns and correlation with pulmonary function. AJR Am J Roentgenol. 2000;174: 1751Ð7.

25.Armanios MY, Chen JJ, Cogan JD, et al. Telomerase mutations in families with idiopathic pulmonary Þbrosis. N Engl J Med. 2007;356:1317Ð26.

26.van Moorsel CH, van Oosterhout MF, Barlo NP, et al. Surfactant protein C mutations are the basis of a signiÞcant portion of adult familial pulmonary Þbrosis in a Dutch cohort. Am J Respir Crit Care Med. 2010;182:1419Ð25.

27.Diaz de Leon A, Cronkhite JT, Katzenstein AL, et al. Telomere lengths, pulmonary Þbrosis and telomerase (TERT) mutations. PLoS One. 2010;5:e10680.

28.Takemura T, Akashi T, Kamiya H, et al. Pathological differentiation of chronic hypersensitivity pneumonitis from idiopathic pulmonary Þbrosis/usual interstitial pneumonia. Histopathology. 2012;61: 1026Ð35.

29.Selman M, Buendia-Roldan I. Immunopathology, diagnosis, and management of hypersensitivity pneumonitis. Semin Respir Crit Care Med. 2012;33:543Ð54.

30.Hansell DM, Wells AU, Padley SP, Muller NL. Hypersensitivity pneumonitis: correlation of individual CT patterns with functional abnormalities. Radiology. 1996;199:123Ð8.

31.Takemura T, Akashi T, Ohtani Y, Inase N, Yoshizawa Y. Pathology

of hypersensitivity pneumonitis. Curr Opin Pulm Med. 2008;14: 440Ð54.

32. Hanak V, Golbin JM, Hartman TE, Ryu JH. High-resolution CT Þndings of parenchymal Þbrosis correlate with prognosis in hypersensitivity pneumonitis. Chest. 2008;134:133Ð8.

33.Rosen Y, Athanassiades TJ, Moon S, Lyons HA. Nongranulomatous interstitial pneumonitis in sarcoidosis. Relationship to development of epithelioid granulomas. Chest. 1978;74:122Ð5.

34.Baughman RP, Winget DB, Bowen EH, Lower EE. Predicting respiratory failure in sarcoidosis patients. Sarcoidosis Vasc Diffuse Lung Dis. 1997;14:154Ð8.

35.Shlobin OA, Nathan SD. Management of end-stage sarcoidosis: pulmonary hypertension and lung transplantation. Eur Respir J. 2012; 39:1520Ð33.