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