Chronic obstructive pulmonary disease (COPD) is a worldwide disease, featured by not fully reversible and progressive airflow limitation, leading to the concurrence of persistent chronic airway inflammation (chronic bronchitis) and permanent parenchyma destruction (emphysema). Pulmonary fibrosis (PF), a restrictive pulmonary disorder, is reported to exist in COPD patients, part of which is defined as a new subtype of combined pulmonary fibrosis and emphysema (CPFE), although the fibrotic regions, severity and even prognosis are varied in different individuals [1].
