A CT chest of a patient with sarcoidosis shows micronodules distributed predominantly along bronchovascular bundles, interlobular septa, and subpleural regions. This distribution is called:

• A Perilymphatic distribution ✓
• B Centrilobular distribution
• C Random distribution
• D Panlobular distribution

Explanation

Sarcoidosis produces micronodules in a perilymphatic distribution — along lymphatic drainage routes including bronchovascular bundles, interlobular septa, pleural surfaces, and fissures. Centrilobular nodules (as in tree-in-bud) are centered in the lobule around bronchioles and arteries, sparing the pleura. Random distribution (as in hematogenous metastases or miliary TB) shows uniform distribution throughout the lobule without preferential site. Panlobular refers to uniform parenchymal involvement such as alpha-1-antitrypsin deficiency emphysema.

Reference: Grainger & Allison's Diagnostic Radiology, 7th ed.

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