Chronic obstructive pulmonary disease in a new concept.

Chronic Obstructive Pulmonary Disease (COPD) is a preventable and treatable disease with some significant extrapulmonary effects that may contribute to the severity in individual patients. Its pulmonary component is characterized by airflow limitation that is not fully reversible. The airflow limitation is usually progressive and associated with an abnormal inflammatory response of the lung to noxious particles or gases. Although COPD is a nonspecific term referring to a set of conditions that develops progressively because of a number of different disease processes, it most commonly refers to patients with chronic bronchitis and emphysema and to a subset of patients with asthma. Several different definitions were proposed for COPD in time. COPD is not asthma but can coexist with asthma, the other major airways obstructive disease caused by airway inflammation. Inflammation underlying in asthma has characteristic features, distinct of that from COPD. Longitudinal studies revealed the heterogeneous character of COPD. The pathological hallmarks of chronic obstructive pulmonary disease (COPD) are inflammation of the small airways (bronchiolitis) and destruction of lung parenchyma (emphysema). International guidelines stress the importance of accurately discriminating between asthma and chronic obstructive pulmonary disease. Although characteristic pathological features have been described for both conditions, their discriminatory power has never been systematically assessed. This might be rectified by improving pathological definitions.