A rare lung disorder characterized by the filling of the pulmonary alveoli with proteinaceous material which stains positive with periodic acid-Schiff stain. It may be idiopathic or secondary due to hematologic malignancies or the inhalation of mineral dusts. Signs and symptoms include dyspnea, cough and low grade fever. The disease is MONDO_0001437 (pulmonary alveolar proteinosis).