Idiopathic Interstitial Pneumonias (IIPs): Review of Clinical, Radiographic and High-Resolution Computed Tomography (HRCT)

Making a confident diagnosis is a complex task for a specific form of interstitial lung disease and providing appropriate management in an attempt to achieve normalization of the disease can put up an alarming process for the clinicians. A set of diffuse and restrictive lung diseases incorporate with idiopathic interstitial pneumonias, showing inflammation and fibrosis of the interstitium due to parenchymal damage. High-resolution computed tomography (HRCT) has magnified the diagnostic standpoint in stepwise identification and classified various patterns in the evaluation of interstitial lung disease. The aim of our review is to elaborate clinical, radiographic and typical and atypical HRCT findings of idiopathic interstitial pneumonias by correlating with its differential diagnosis. Idiopathic pulmonary fibrosis is the most predominant idiopathic interstitial pneumonias and its diagnosis needs to omit all other well-known causes of interstitial lung diseases. According to the 2011 evidence-based guidelines, usual interstitial pneumonia can be diagnosed by HRCT when all criteria are fulfilled. Non-specific interstitial pneumonia is distinguished by bilateral patchy ground-glass opacities and irregular linear/reticular opacities. Respiratory bronchiolitis associated-interstitial lung disease and desquamative interstitial pneumonia show centrolobular nodules and ground-glass opacities as imaging patterns. Cryptogenic organizing pneumonia consists of patchy peripheral or peribronchial consolidations, while ground-glass opacities with tendency for migration, which is evolving to fibrosis, in acute interstitial pneumonia. Lymphoid interstitial pneumonia and idiopathic pleuro-parenchymal fibroelastosis are classified under rare idiopathic interstitial pneumonias. HRCT images help radiologists in diagnosis and mapping specific patterns of idiopathic interstitial pneumonias. This article reviews the stages of evolution in HRCT features for idiopathic interstitial pneumonias.