Diagnosis of Idiopathic Pulmonary Fibrosis: Differential Diagnosis

Abstract

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, and fibrotic interstitial lung disease of unknown origin with a characteristic imaging and histologic pattern called usual interstitial pneumonia (UIP). The diagnosis of IPF is a complex procedure that requires the support of various specialists, who must integrate clinical, radiological, and histological data. The multidisciplinary team (MDT) has become the new gold standard to diagnose and manage the disease, increasing the accuracy and agreement of the diagnosis between different centers. It is mandatory to exclude nonspecific interstitial pneumonia or other diseases that can cause the UIP pattern, particularly drugs or exposure diseases, including chronic hypersensitivity pneumonitis or systemic autoimmune disease. The role of the MDT is also to decide who could need a biopsy or to review patient diagnoses at regular intervals in those with additional information or unexpected evolution. This review provides updated information to achieve a proper IPF diagnosis.

Keywords: diagnosis; high-resolution computed tomography; idiopathic interstitial pneumonia; idiopathic pulmonary fibrosis lower case; multidisciplinary team; surgical lung biopsy; transbronchial cryobiopsy; usual interstitial pneumoniae.

Figure 1

Flow chart to diagnose idiopathic pulmonary fibrosis (IPF). ILD: interstitial lung disease; HRCT: high-resolution computed tomography; UIP: usual interstitial pneumonia; MDT: Multidisciplinary team; SLB: surgical lung biopsy; TBB: transbronchial forceps biopsy; BAL: bronco alveolar lavage; *: patient with “probable UIP pattern” in high-resolution computed tomography (HRCT) and clinical high suspicion of IPF (patient over 60 years, smoking history, and unknown etiology do not require a biopsy).

Figure 2

HRCT in IPF. (A) Typical UIP CT pattern. HRCT image: honeycombing (circle) and reticular opacities with peripheral traction bronchiectasis (arrows), with peripheral subpleural and basal-predominant distribution. (B) CT pattern indeterminate for UIP and acute exacerbation. (B.1) HRCT image: reticular abnormalities with traction bronchiectasis and non-basal predominance (circle). (B.2) HRCT image in left decubitus lateral six months after the previous examination: multifocal areas of ground glass opacities, overlapped with the previous pattern of pulmonary fibrosis. (C) Probable UIP CT pattern. (C.1–3) HRCT images: reticular pattern with traction bronchiectasis (arrows in C.2 and C.3) and a peripheral subpleural and basal predominance; peripheral reticulation is non-segmental (crossing fissures), heterogeneous, and present in upper lobes. Note that there is no honeycombing, and the UIP histological pattern was proven with pulmonary biopsy. (D) IPF and lung adenocarcinoma. (A,D.1) HRCT images: typical UIP CT asymmetrical pattern and lung mass in the apical segment of the left lower lobe (star in D.2).