A 68-year-old coal miner with a history of smoking and emphysema develops severe air-flow obstruction and expires. Autopsy reveals a "black lung," with coal-dust nodules scattered throughout the parenchyma and a central area of dense fibrosis. The coal dust entrapped within this miner's lung was sequestered primarily by which of the following cells?

Macrophages. Coal workers' pneumoconiosis reflects the inhalation of carbon particles. The characteristic pulmonary lesions of simple coal worker's pneumoconiosis include nonpalpable coal-dust macules and palpable coal-dust nodules, both of which are typically multiple and scattered throughout the lung as 1- to 4-mm black foci. Nodules consist of dust-laden macrophages associated with a fibrotic stroma. Nodules occur when coal is admixed with fibrogenic dusts such as silica and are more properly classified as anthracosilicosis. Coal-dust macules and nodules appear on a chest radiograph as small nodular densities. The other choices are not phagocytic cells.Diagnosis: Anthracosilicosis, coal workers' pneumoconiosis