Idiopathic Pulmonary Fibrosis: A Historical Perspective

Abstract

The term “idiopathic pulmonary fibrosis” (IPF) began to appear in the medical literature in the mid-1900s and was initially used by clinicians and radiologists to refer to fibrosing pneumonitis of unknown cause. However, the entities that we now recognize as idiopathic interstitial pneumonias (IIPs) and other entities with similar clinical presentations, such as interstitial lung disease (ILD) associated with connective tissue disorders (CTD) or fibrotic hypersensitivity pneumonitis (HP), were often identified as cases of IPF by clinicians due to similar clinical presentation and radiographic appearance. As our knowledge of fibrosing ILD expanded over the last three decades of the twentieth century, it became clear that histopathologic patterns could be found that paved the way to our current clinicopathologic classification of the IIPs, with the term “IPF” used exclusively to designate patients with idiopathic usual interstitial pneumonia (UIP). This introductory chapter will review how terminology and concepts of the disorder that we now recognize as IPF have evolved over the decades such that IPF has become the preferred diagnostic term for patients diagnosed with UIP of unknown cause.