BASICS OF HRCT PART 7 - DIFFERENTIAL DIAGNOSIS OF ILD

This is the last post in the series of basics of HRCT. links to the previous posts are given at the end of this post.

DIFFERENTIAL DIAGNOSIS OF INTERSTITIAL LUNG DISEASE
Reticular pattern 

1.     Lymphangitic carcinomatosis: irregular septal thickening, usually focal or unilateral 50% adenopathy', known carcinoma.
2.     Cardiogenic pulmonary edema: incidental finding in HRCT, smooth septal thickening with basal predominance (Kerley B lines), ground-glass opacity with a gravitational and perihilar distribution, thickening of the peribronchovascular interstitium (peribronchial cuffing)
3.     Lymphangitic carcinomatosis.
4.     Lymphangitic carcinomatosis with hilar adenopathy.
5.     Alveolar proteinosis: ground glass attenuation with septal thickening (crazy paving).
6.     Cardiogenic pulmonary edema.


Nodular pattern

1.     Hypersensitivity pneumonitis: ill defined centrilobular nodules.
2.     Miliary TB: random nodules
3.     Sarcoidosis: nodules with perilymphatic distribution, along fissures, adenopathy.
4.     Hypersensitivity pneumonitis: centrilobular nodules, notice sparing of the area next to pleura and fissure.

Nodular pattern(2)

1.     Sarcoidosis: nodules with perilymphatic distribution, along fissures, adenopathy.
2.     TB: Tree-in-bud appearance in a patient with active TB.
3.     Langerhans cell histiocytosis: early nodular stage before the typical cysts appear.
4.     Respiratory bronchiolitis in infection.

High Attenuation pattern 



1.     Chronic eosinophilic pneumonia with peripheral areas of ground glass opacity.
2.     Sarcoid end-stage with massive fibrosis in upper lobes presenting as areas of consolidation. Notice lymphadenopathy.
3.     Chronic eosinophilic pneumonia with peripheral areas of consolidation.
4.     Broncho-alveolar cell carcinoma with both areas of ground glass opacity and consolidation

High Attenuation pattern (2) 



1.     Non specific interstitial pneumonitis (NSIP): ground glass with traction bronchiectasis, no honeycombing.
2.     Cryptogenic organizing pneumonia (COP).
3.     Sarcoidosis end-stage: consolidation as a result of massive fibrosis perihilar and in upper lobes.
4.     COP.

Low Attenuation pattern 



1.     Lymphangiomyomatosis (LAM): uniform cysts in woman of child-bearing age; no history of smoking; adenopathy and pleural effusion; sometimes pneumothorax.
2.     LCH: multiple round and bizarre shaped cysts; smoking history.
3.     Honeycombing
4.     Centrilobular emphysema: low attenuation areas without walls.

Low Attenuation pattern (2) 



1.     Centrilobular emphysema: low attenuation areas without walls. Notice the centrilobular artery in the center.
2.     Langerhans cell histiocytosis (LCH): multiple thick walled cysts; smoking history.
3.     Honeycombing.

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