Silicosis
Summary
Pneumoconiosis caused by inhalation of silica dust, classically in sandblasters, miners, and foundry workers. Produces upper-lobe nodular fibrosis and dramatically increases susceptibility to tuberculosis.
Detail
Silica is phagocytosed by alveolar macrophages, which release IL-1, TNF-alpha, and reactive oxygen species, driving fibroblast activation and collagen deposition. Imaging shows upper-lobe nodules, 'eggshell' calcification of hilar lymph nodes, and in advanced cases progressive massive fibrosis. Silica impairs macrophage killing of Mycobacterium tuberculosis, markedly raising TB risk (silicotuberculosis). Also linked to increased risk of bronchogenic carcinoma (IARC group 1 carcinogen) and Caplan syndrome when combined with rheumatoid arthritis. Histology shows birefringent silica particles within fibrotic, whorled nodules.
Sources
- First Aid for USMLE Step 1 2024
- Robbins Basic Pathology 10th ed
- Pathoma
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