<prompt> 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 miners lung was sequestered primarily by which of the following cells?Endothelial cellsFibroblastsLymphocytesMacrophages  <response>: Macrophages. Coal workers pneumoconiosis reflects the inhalation of carbon particles. The characteristic pulmonary lesions of simple coal workers 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 