Combined Pulmonary Fibrosis and Emphysema: A Narrative Review

Combined pulmonary fibrosis and emphysema (CPFE) syndrome refers to co-occurrence of two disease processes in the lung that can be difficult to diagnose but is associated with high morbidity and mortality burden. Diagnosis of CPFE is challenging because the two diseases can counterbalance respective impairments resulting in deceivingly normal-appearing chest radiography and spirometry in a dyspneic patient. Although an international committee published the terminology and definitions of CPFE in 2022, consensus on exact diagnostic criteria and optimal management strategy is yet to be determined. Herein, we provide a narrative review summarizing the literature on CPFE from 1990 to 2022, including historical background, epidemiology, pathogenesis, clinical features, imaging and pulmonary function findings, diagnosis, prognosis, complications, and treatment. Although CPFE was initially conceived as a variant presentation of idiopathic pulmonary fibrosis, it has been recognized to occur in patients with a wide variety of interstitial lung diseases, including connective tissue disease-associated interstitial lung diseases, and hypersensitivity pneumonitis. The affected patients have a heightened risk for pulmonary hypertension and lung cancer. Clinicians need to recognize the characteristic presenting features of CPFE along with prognostic implications of this entity.