Pulmonary Thromboembolic Disease

Infarcts are aggregates of infarcted secondary pulmonary lobules. Infarction of a single lobule can occur. Application of a lobular concept of thromboembolic d1sease provides a morphologic basis which partly explains the limitations inherent in plain film diagnosis. Infarcts have no predictable configuration. Thromboembolism may cause hemorrhage indistinguishable radiographically from pneumonia or edema. When the infarct is surrounded by hemorrhage, when there is admixture of infarcted and viable lobules at the infarct margin, and when interface between infarcted and viable lobules is not parallel to the x-ray beam, the poorly defined infarct outlines may make differentiation from pneumonia or edema impossible.