hand-schuller-christian disease: inflammatory histiocytosis associated with disturbance of cholesterol metabolism; occurs chiefly in young children and is characterized by cystic defects of the skull and diabetes insipidus
histiocytosis: a blood disease characterized by an abnormal multiplication of macrophages
pneumothorax: abnormal presence of air in the pleural cavity resulting in the collapse of the lung; may be spontaneous (due to injury to the chest) or induced (as a treatment for tuberculosis)