Interstitial Pneumonia with Autoimmune Features and Undifferentiated Connective Tissue Disease

In 2015, a multidisciplinary task force comprising pulmonologists, rheumatologists, pathologists, and radiologists representing the European Respiratory Society and American Thoracic Society published a diagnostic classification schema for individuals with interstitial lung disease and autoimmune features who did not meet criteria for a defined connective tissue disease. The term interstitial pneumonia with autoimmune features (IPAF) was applied. Classification criteria are often nonspecific, but up to 90% of subjects with IPAF have serological evidence for autoimmunity (particularly (+) antinuclear antibodies). Distinguishing patients with IPAF from idiopathic pulmonary disorders may be difficult. The natural history and appropriate management of IPAF have not been clarified, as data are largely limited to retrospective studies. In this review, we discuss the salient clinical, serologic, histologic, and radiographic features of IPAF and discuss an approach to management.