Pracical Aproach to Interstitial Lung Diseases

1. By: Nour-Eldin A. Nour-Eldin Pracical Aproach to Interstitial Lung Diseases

2. The Lung Interstitium The interstitium of the lung is not normally visible radiographic- ally; it becomes visible only when disease (e.g., edema, fibrosis, tumor) increases its volume and attenuation. The interstitial space is defined as continuum of loose connective tissue throughout the lung composed of three subdivisions: (i) the bronchovascular (axial), surrounding the bronchi, arteries, and veins from the lung root to the level of the respiratory bronchiole (ii) the parenchymal (acinar), situated between the alveolar and capillary basement membranes (iii) the subpleural, situated beneath the pleura, as well as in the interlobular septae.

4. Patterns of Interstitial Lung Disease • Interstitial lung disease may result in four patterns of abnormal opacity on chest radiographs and CT scans: linear, reticular, nodular, and reticulonodular • These patterns are more accurately and specifically defined on CT

5. Patterns of Interstitial Lung Disease

6. Linear Pattern A linear pattern is seen when there is thickening of the interlobular septa, producing Kerley lines. Kerley B lines Kerley A lines The interlobular septa contain pulmonary veins and lymphatics. The most common cause of interlobular septal thickening, producing Kerley A and B lines, is pulmonary edema, as a result of pulmonary venous hypertension and distension of the lymphatics. Kerley A lines Kerley B lines

7. DD of Kerly Lines: Pulmonary edema is the most common cause Mitral stenosis Lymphangiticcarcinomatosis Malignant lymphoma Congenital lymphangiectasia Idiopathic pulmonary fibrosis Pneumoconiosis Sarcoidosis

9. b. Reticular Pattern A reticular pattern results from the summation or superimposition of irregular linear opacities. The term reticular is defined as meshed, or in the form of a network. Reticular opacities can be described as fine, medium, or coarse, as the width of the opacities increases. A classic reticular pattern is seen with pulmonary fibrosis, in which multiple curvilinear opacities form small cystic spaces along the pleural margins and lung bases (honeycomb lung)

10. This 50-year-old man presented with end-stage lung fibrosis PA chest radiograph shows medium to coarse reticular B: CT scan shows multiple small cysts (honeycombing) involving predominantly the subpleural peripheral regions of lung. Traction bronchiectasis, another sign of end-stage lung fibrosis.

11. c. Nodular pattern • A nodular pattern consists of multiple round opacities, generally ranging in diameter from 1 mm to 1 cm • Nodular opacities may be described as miliary(1 to 2 mm, the size of millet seeds), small, medium, or large, as the diameter of the opacities increases • A nodular pattern, especially with predominant distribution, suggests a specific differential diagnosis

12. Disseminated histoplasmosis and nodular ILD. CT scan shows multiple bilateral round circumscribed pulmonary nodules.

13. Hematogenous metastases and nodular ILD. This 45-year-old woman presented with metastatic gastric carcinoma. The PA chest radiograph shows a diffuse pattern of nodules, 6 to 10 mm in diameter.

14. Differential diagnosis of a nodular pattern of interstitial lung disease SHRIMP Sarcoidosis Histiocytosis (Langerhan cell histiocytosis) Hypersensitivity pneumonitis Rheumatoid nodules Infection (mycobacterial, fungal, viral) Metastases Microlithiasis, alveolar Pneumoconioses (silicosis, coal worker's, berylliosis)

15. d. Reticulonodular pattern results A reticulonodular pattern results from a combination of reticular and nodular opacities. This pattern is often difficult to distinguish from a purely reticular or nodular pattern, and in such a case a differential diagnosis should be developed based on the predominant pattern. If there is no predominant pattern, causes of both nodular and reticular patterns should be considered.

16. How To Approach a Practical Diagnosis?

17. Rule no. 1 An acute appearance suggests pulmonary edema or pneumonia

18. Disseminated histoplasmosis and reticulonodular ILD. A: PA chest radiograph, close-up of right upper lung, shows reticulonodular ILD. B: CT scan shows multiple circumscribed round pulmonary nodules, 2 to 3 mm in diameter.

19. Rule no. 2 Reticulonodularlower lung predominant distribution with decreased lung volumes suggests: (APC) 1. Asbestosis 2. Aspiration (chronic) 3. Pulmonary fibrosis (idiopathic) 4.Collagen vascular disease

20. Asbestos-related pleural disease and asbestosis

21. Pulmonary fibrosis and rheumatoid arthritis.

22. Systemic sclerosis. A: PA chest radiograph shows a bibasilar and subpleural distribution of fine reticular ILD. The presence of a dilated esophagus (arrows) provides a clue to the correct diagnosis. B: CT scan shows peripheral ILD and a dilated esophagus (arrow).

23. Rule no. 3 A middle or upper lung predominant distribution suggests: (Mycobacterium Settle Superiorly in Lung) Mycobacterial or fungal disease Silicosis Sarcoidosis Langerhans Cell Histiocytosis

24. Complicated silicosis. PA chest radiograph shows multiple nodules involving the upper and middle lungs, with coalescence of nodules in the left upper lobe resulting in early progressive massive fibrosis

25. Sarcoidosis. CT scan shows nodular thickening of the bronchovascular bundles (solid arrow) and subpleural nodules (dashed arrow), illustrating the typical perilymphatic distribution of sarcoidosis.

26. Langerhan cell histiocytosis. This 50-year-old man had a 30 pack-year history of cigarette smoking. A: PA chest radiograph shows hyperinflation of the lungs and fine bilateral reticular ILD. B: CT scan shows multiple cysts (solid arrow) and nodules (dashed arrow).

27. Rule no. 4 Associated lymphadenopathy suggests : 1.Sarcoidosis 2.neoplasm (lymphangiticcarcinomatosis, lymphoma, metastases) 3. infection (viral, mycobacterial, or fungal) 4. silicosis

28. Simple silicosis. A: CT scan with lung windowing shows numerous circumscribed pulmonary nodules, 2 to 3 mm in diameter (arrows). B: CT scan with mediastinal windowing shows densely calcified hilar (solid arrows) and subcarinal (dashed arrow) nodes.

29. Rule no. 5 Associated pleural thickening and/or calcification suggest asbestosis.

30. Rule no. 6 Associated pleural effusion suggests : 1.pulmonary edema 2.lymphangitic carcinomatosis 3.lymphoma 4.collagen vascular disease

31. Cardiogenic pulmonary edema. PA chest radiograph shows enlargement of the cardiac silhouette, bilateral ILD, enlargement of the azygos vein (solid arrow), and peribronchial cuffing (dashed arrow).

32. Lymphangiticcarcinomatosis. This 53-year-old man presented with chronic obstructive pulmonary disease and large-cell bronchogenic carcinoma of the right lung. CT scan shows unilateral nodular thickening (arrows) and a malignant right pleural effusion.

33. Rule no. 7 Associated pneumothorax suggests lymphangioleiomyomatosis or LCH.

34. Lymphangioleiomyomatosis (LAM). A: PA chest radiograph shows a right basilar pneumothorax and two right pleural drainage catheters. The lung volumes are increased, which is characteristic of LAM, and there is diffuse reticular ILD. B: CT scan shows bilateral thin-walled cysts and a loculated right pneumothorax (P).

35. Tell me the rules again?

36. 1. Acute 2. Pleural effusion 3.Pneumothorax 4.Predominantly Below with reduced volume • P.Edema • Pneumonia • 1.pulmonary edema • 2.lymphangitic carcinomatosis • 3.lymphoma • 4.collagen vascular disease • lymphangioleiomyomatosis • LCH 1.Asbestosis 2. Aspiration (chronic) 3. Pulmonary fibrosis (idiopathic) 4.Collagen vascular disease

37. 6. Associated lymphadenopathy 5. A middle or upper lung predominant 7. Pleural Thickening and or Calcification Mycobacterial or fungal disease Silicosis Sarcoidosis Langerhans Cell Histiocytosis • Asbestosis 1.Sarcoidosis 2.neoplasm (lymphangiticcarcinomatosis, lymphoma, metastases) 3. infection (viral, mycobacterial, or fungal) 4. silicosis

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