A 35-year-old woman with known sarcoidosis has HRCT showing bilateral hilar and mediastinal lymphadenopathy with bilateral perihilar nodularity along bronchovascular bundles. Which CT description best characterizes pulmonary sarcoidosis?
- A Centrilobular nodules with tree-in-bud pattern
- B Perilymphatic distribution of nodules — along bronchovascular bundles, interlobular septa, and subpleural regions ✓
- C Random distribution of miliary nodules
- D Predominantly ground-glass opacity with crazy-paving pattern
Explanation
Pulmonary sarcoidosis has a characteristic perilymphatic distribution of nodules on HRCT — non-caseating granulomas form along the lymphatic pathways of the lung, producing nodules along bronchovascular bundles, interlobular septa, and subpleural/fissural surfaces. This is the cardinal HRCT feature distinguishing sarcoidosis from other granulomatous diseases. Tree-in-bud pattern indicates bronchiolar impaction (endobronchial spread of TB, atypical mycobacteria). Miliary random pattern suggests hematogenous dissemination. Crazy-paving (ground-glass + interlobular septal thickening) is seen in PAP and some infections.
Reference: Grainger & Allison's Diagnostic Radiology, 7th ed.
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