<prompt> Macrophages with abundant cytoplasm containing dusty brown pigment are seen inDesquamative Interstitial PneumoniaPulmonary Alveolar ProteinosisPulmonary Langerhans Cell HistiocytosisPulmonary Eosinophilia  <response>: Desquamative interstitial pneumonia is characterized by large collections of macrophages in the airspaces in a current or former smoker. The macrophages were originally thought to be desquamated pneumocytes, thus the misnomer desquamative interstitial pneumonia.The most striking finding is the accumulation of a large number of macrophages with abundant cytoplasm containing dusty brown pigment smokers macrophages in the airspaces.Ref: Robbins and Cotran Pathologic basis of DIsease; 9th edition; Chapter 15; The lung; Change 682 