Hypereosinophilic syndrome with pulmonary vascular involvement

We have studied a patient with hypereosinophilic syndrome (HES) who initially presented with recurrent asthmatic attacks followed by progressive dyspnea. Chronic obstructive lung disease was suspected at first although involvement of cardiac and other organ systems and marked eosinophilia eventually led to the diagnosis. Thereafter a diffuse interstitial pattern gradually developed on the chest radiograph which persisted despite vigorous treatment for cardiac failure. This was due to infiltration and cuffing of the small pulmonary arteries by eosinophils. The bronchi showed changes consistent with asthma. Review of the literature indicates that this type of vascular change is common in HES but involves predominantly organs other than the lung. Similar pulmonary arterial changes have been produced experimentally in the calf by prolonged intravenous infusion of antibiotics, indicating that this may be a hypersensitivity reaction to a blood-borne material entering the pulmonary circulation.