Pulmonary veno-occlusive disease in the middle-aged.

Pulmonary veno-occlusive disease (PVO) is an uncommon cause of pulmonary hypertension which is difficult to diagnose without histology. We report 3 cases of histologically confirmed PVO. Our patients were all middle-aged or older, and 1 had spontaneous improvement in his symptoms suggesting that PVO may occur more commonly among older adults than previously believed and that indolent forms of the disease may exist. As new therapeutic approaches to the various entities causing pulmonary hypertension are developed, it is increasingly important to determine precisely which condition is present in a given patient.