anthracosis

Macrophages in alveoli engulf inhaled carbon particles and traffic them along lymphatics to peribronchial and hilar lymph nodes, where they accumulate as black pigment without significant fibrosis or functional impairment. Anthracosis is essentially universal in urban dwellers and smokers and is the mildest manifestation of carbon exposure. With heavier occupational coal dust exposure it progresses to simple coal worker's pneumoconiosis (coal macules — 1–2 mm collections of dust-laden macrophages around respiratory bronchioles, upper-lobe predominant) and then to complicated CWP / progressive massive fibrosis (coalescent black scars >1 cm with restrictive lung disease and cor pulmonale). Anthracotic pigment in lymph nodes is a useful endogenous landmark during mediastinoscopy.