|
Pattern | Histology | CT features | CT differential diagnosis |
|
UIP | Subpleural and peripheral fibrosis. Fibroblastic foci, lymphoid aggregates with germinal centres and honeycombing are characteristic. Mild inflammation; architectural destruction. | Peripheral, subpleural, basal reticulation, and honeycombing Traction bronchiectasis, architectural distorsion, GGO (less diffuse). Subpleural lines | IPF, other collagen vascular diseases, hypersensitivity pneumonitis (micronodules and sparing of lung bases), sarcoidosis, asbestosis (pleural thickening). |
|
NSIP | Uniform interstitial involvement; various degrees of fibrosis and/or inflammation. Lymphoid aggregates. Rare honeycombing | Bilateral, symmetrical, patchy, mainly basal GGO, possible reticulation, traction bronchiectasis, irregular lines, or consolidation. Little or no honeycombing (in fibrosing NSIP). | UIP, DIP, COP, hypersensitivity pneumonitis, and HIV-associated interstitial lung disease. |
|
OP | Connective tissue plugs within small airways and air spaces (Masson bodies). Little or no inflammation or fibrosis. | Patchy and multiple airspace consolidation, mainly basal, peripheral, or peribronchovascular. Air bronchograms can be seen. Possible associated GGO or centrilobular nodules. | Infections, vasculitis, sarcoidosis, alveolar carcinoma, lymphoma, eosinophilic pneumonia, NSIP, and COP. |
|
DAD | (i) Acute phase: hyaline membranes, edema. (ii) Organizing phase: airspace and interstitial organization | (i) Acute phase: progressive, patchy, or diffuse GGO and dependent consolidation, often with lobular sparing (ii) Organizing phase: reticulation, traction bronchiectasis, and architectural distorsion. | Hydrostatic edema, pneumonia, eosinophilic pneumonia, and ARDS (but more symmetrical and lower lung zones) |
|
DIP | Extensive macrophage accumulation in the distal air spaces. Mild interstitial involvement. | Patchy GGO, basal, and peripheral. Microcystic changes within GGO, reticular lines. | RB-ILD, hypersensitivity pneumonitis, sarcoidosis, and Pneumocystis jiroveci pneumonia. |
|
RB-ILD | Bronchiolocentric macrophage accumulation. Mild bronchiolar fibrosis | Diffuse/upper lobes distribution, centrilobular nodules, bronchial wall thickening, and patchy GGO. | DIP, NSIP, and hypersensitivity pneumonitis |
|
LIP | Bronchiolocentric lymphoid tissue hyperplasia | Diffuse, GGO, centrilobular nodules, septal and bronchovascular thickening, thin-walled cysts, and lymph node enlargement. | Sarcoidosis, lympangitic carcinoma, and Langherans’ cell histiocytosis |
|