Unusual appearance of thromboembolism on perfusion lung imaging.

A 46-year-old woman with advanced ovarian carcinoma had progressive dyspnea and was evaluated with ventilation and perfusion lung imaging. A characteristic pattern of multiple branching perfusion defects of a segmental nature on the perfusion scan suggested tumor microembolism and lymphangitic carcinomatosis. However, in this case, this pattern was associated with pulmonary thromboembolism and was documented by the post mortem examination. Pulmonary thromboembolism should be included among the differential diagnoses in a patient with clinical symptoms and a perfusion scan that reveals multiple branching perfusion defects.