dust cells
Summary
Pulmonary alveolar macrophages that phagocytose inhaled particulates and pathogens. Hemosiderin-laden dust cells in sputum/BAL are 'heart failure cells,' seen in chronic pulmonary edema.
Detail
Dust cells are tissue-resident macrophages residing in the alveolar lumen, derived primarily from fetal yolk sac/liver precursors with contribution from circulating monocytes. They are critical for innate immunity in the lung: they phagocytose dust, pathogens, and surfactant, present antigen, and secrete cytokines. In left-sided heart failure or chronic pulmonary congestion, RBCs extravasate into alveoli and are engulfed by these macrophages, which break down hemoglobin into hemosiderin, producing characteristic 'heart failure cells' with golden-brown intracytoplasmic pigment (Prussian blue positive). They are also key in coal worker's pneumoconiosis (anthracotic) and silicosis.
Sources
- First Aid for USMLE Step 1 2024
- Robbins Basic Pathology 10th ed
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