Pulmonary edema is a common clinical entity caused by the extravascular movement of fluid into the pulmonary interstitium and alveoli. The four physiologic categories of edema include hydrostatic pressure edema, permeability edema with and without diffuse alveolar damage (DAD), and mixed edema where there is both an increase in hydrostatic pressure and membrane permeability. As radiographic manifestations and etiologies are varied, an appreciation for both the common and uncommon manifestations and causes of pulmonary edema is essential for accurate diagnosis.
