Idiopathic Pulmonary Fibrosis

Subpleural honeycombing and traction bronchiectasis (signet ring sign, where multiple thickened dilated bronchi are seen below a pulmonary artery) are present on high-resolution CT in a patient with idiopathic pulmonary fibrosis (IPF). Findings inconsistent with IPF, such as nodules, are absent. These CT findings are virtually diagnostic of IPF if clinical findings are compatible.