A 40-year-old man with restrictive lung disease and dyspnoea on exertion undergoes lung biopsy showing non-necrotising granulomas in a perilymphatic distribution along bronchovascular bundles, interlobular septa, and pleura. Serum ACE is elevated. The diagnosis is sarcoidosis. The perilymphatic distribution of granulomas in sarcoidosis is BEST seen on which imaging modality?
- A PET-CT showing FDG-avid pulmonary infiltrates without lymph node involvement
- B Plain chest X-ray showing bilateral upper lobe fibrocystic disease only
- C High-resolution CT (HRCT) showing nodules in bronchovascular, perilobular, and subpleural locations ✓
- D V/Q scan showing segmental perfusion defects without ventilation defects
Correct answer: C. High-resolution CT (HRCT) showing nodules in bronchovascular, perilobular, and subpleural locations
Explanation
HRCT is the investigation of choice for demonstrating the perilymphatic distribution of sarcoid granulomas: nodules along bronchovascular bundles, interlobular septa (beaded septa sign), and subpleural surfaces in a predominantly upper and mid-lung distribution, along with bilateral hilar adenopathy. PET-CT is used for disease activity assessment; V/Q scan is for pulmonary embolism.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
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