Usual interstitial pneumonia

Usual interstitial pneumonia (UIP) is a form of lung disease characterized by progressive scarring of both lungs. The scarring (fibrosis) involves the supporting framework (interstitium) of the lung. UIP is thus classified as a form of interstitial lung disease. Appearance of usual interstitial pneumonia (UIP) in a surgical lung biopsy at low magnification. The tissue is stained with hematoxylin (purple dye) and eosin (pink dye) to make it visible. The pink areas in this picture represent lung fibrosis (collagen stains pink). Note the 'patchwork' (quilt-like) pattern of the fibrosis.Appearance of honeycomb change in a surgical lung biopsy at low magnification. The dilated spaces seen here are filled with mucin. Hematoxylin-eosin stain, low magnification.A fibroblast focus in a surgical lung biopsy of UIP. Hematoxylin-eosin stain, high magnification. The white space to the left is an airspace. The pale area to the right is a fibroblast focus. It is an area of active fibroblast proliferation within the interstitium of the lung. Usual interstitial pneumonia (UIP) is a form of lung disease characterized by progressive scarring of both lungs. The scarring (fibrosis) involves the supporting framework (interstitium) of the lung. UIP is thus classified as a form of interstitial lung disease. The term 'usual' refers to the fact that UIP is the most common form of interstitial fibrosis. 'Pneumonia' indicates 'lung abnormality', which includes fibrosis and inflammation. A term previously used for UIP in the British literature is cryptogenic fibrosing alveolitis (CFA), a term that has fallen out of favor since the basic underlying pathology is now thought to be fibrosis, not inflammation. The term usual interstitial pneumonitis (UIP) has also often been used, but again, the -itis part of that name may overemphasize inflammation. The typical symptoms of UIP are progressive shortness of breath and cough for a period of months. In some patients, UIP is diagnosed only when a more acute disease supervenes and brings the patient to medical attention. The cause of the scarring in UIP may be known (less commonly) or unknown (more commonly). Since the medical term for conditions of unknown cause is 'idiopathic', the clinical term for UIP of unknown cause is idiopathic pulmonary fibrosis (IPF). Examples of known causes of UIP include connective tissue diseases (primarily rheumatoid arthritis), drug toxicity, chronic hypersensitivity pneumonitis, asbestosis and Hermansky–Pudlak syndrome.