Pulmonary embolism with unilateral lung scan defects and matching infiltrates.

Ten patients with matching ventilation-perfusion lung scan defects and corresponding pulmonary infiltrates were evaluated with segmental pulmonary angiography. All ten patients presented with sudden onset of pleuritic chest pain and fever. Pulmonary emboli were documented in three of the ten patients (30%). The remaining seven patients had pneumonia or atelectasis. The findings emphasize the non-diagnostic nature of lung scans which show only matching ventilation and perfusion defects in regions of pulmonary infiltrates. Segmental pulmonary angiography is recommended for differentiating pulmonary embolism from atelectasis or pneumonia in these patients.