BASICS OF HRCT PART 6 - DISTRIBUTION PATTERN AND ADDITIONAL FEATURES

Upper lung zone preference is seen in:

• Inhaled particles: pneumoconiosis (silica or coal)
• Smoking related diseases (centrilobular emphysema
• Respiratory bronchiolitis (RB-ILD)
• Langerhans cell histiocytosis
• Hypersensitivity pneumonitis
• Sarcoidosis

Lower zone preference is seen in:

• UIP
• Aspiration
• Pulmonary edema

Central distribution is seen in sarcoidosis and cardiogenic pulmonary edema.

Peripheral distribution is mainly seen in cryptogenic organizing pneumonia (COP), chronic eosinophilic pneumonia and UIP.

Additional findings

Pleural effusion is seen in:

1.     Pulmonary edema

2.     Lymphangitic spread of carcinoma - often unilateral

3.     Tuberculosis

4.     Lymphangiomyomatosis (LAM)

5.     Asbestosis

Hilar and mediastinal lymphadenopathy

In sarcoidosis the common pattern is right paratracheal and bilateral hilar adenopathy ('1-2-3-sign').
In lung carcinoma and lymphangitic carcinomatosis adenopathy is usually unilateral.
'Eggshell calcification' in lymph nodes commonly occurs in patients with silicosis and coal-worker's pneumoconiosis and is sometimes seen in sarcoidosis, postirradiation Hodgkin disease, blastomycosis and scleroderma .

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