A retired shipyard worker has progressive dyspnea. HRCT shows lower lobe predominant subpleural fibrosis with rounded atelectasis and pleural plaques with calcification. Lung biopsy shows interstitial fibrosis beginning around respiratory bronchioles. The diagnostic structures within the fibrotic tissue stain positively with Prussian blue because they are coated with:

• A Silica particles
• B Coal dust
• C Iron and calcium salts around asbestos fibers ✓
• D Beryllium complexes

Explanation

Ferruginous bodies are asbestos fibers engulfed by macrophages and coated with an iron-containing proteinaceous material plus calcium, hence their golden brown beaded appearance and positivity on Prussian blue stain. They are the hallmark of asbestos exposure. Silica produces birefringent particles visible under polarized light without an iron coat, and coal dust forms carbon pigment within macrophages rather than coated fibers.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.