Idiopathic pulmonary fibrosis (IPF) is the most common type of idiopathic interstitial pneumonia (IIP).
Clinical presentation and pathology
Pathologically, IPF is manifested by fibrosis, with scattered fibroblasts around apparent fibrotic lesions. In severe patients, changes in lung structure, honeycomb lung, and traction bronchiectasis are present. IPF is more common in middle-aged individuals, and males are more affected than females. Clinical manifestations include insidious onset, gradually exacerbating dry cough, and progressive dyspnea, with or without clubbed of fingers (toes), as well as dyspnea and cor pulmonale in the late stage.
Imaging manifestations
IPF imaging examinations mainly rely on x-ray and CT, especially thin-section high-resolution CT, which can show clearly early pulmonary fibrosis changes.
X-ray and CT
In the early stage, chest film may be basically normal, but ground-glass opacity can be seen on CT, often in the posterior part of the two lower lungs.
In the progressive stage, diffuse reticular or reticulonodular opacities can be seen in both lungs, which start from the lower lungs, particularly in the posterolateral lower lungs and subpleural areas, and expand to the middle and upper lung fields and the inner and middle zones. Traction bronchiectasis is common.
In the late stage, multiple, 3 - 15 mm in diameter, diffuse, cystic lucencies in both lungs, with honeycomb changes, can be seen.
Figure 1 Idiopathic pulmonary fibrosis
a, b. Thin-section high-resolution CT shows a, thickening of the interlobular interstitium in both lower lungs, forming reticular opacities, accompanied by traction bronchiectasis; b, honeycomb changes in lower lungs, more significant in the left lower lung.
Diagnosis and differential diagnosis
IPF lacks characteristic manifestations in the early stage, and has certain characteristic imaging manifestations in the middle and late stages. Based on imaging and clinical manifestations, a suggestive diagnosis can generally be established. This disease needs to be differentiated from secondary interstitial lung changes caused by systemic connective tissue diseases such as rheumatoid disease and scleroderma; the former has progressive necrotic nodules, namely granulomas, and pleural effusion on the basis of pulmonary fibrosis; the latter has skin changes and decreased tension or stenosis in esophagography. Other connective tissue diseases have interstitial lung changes and corresponding extrapulmonary manifestations.