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 character istic pattern of multiple branching perfusion defects of a segmental nature on the perfusion scan suggested tumor microembolism and lymphangitic carci nomatosis. However, in this case, this pattern was associated with pulmonar y thromboembolism and was documented by the post mortem examination. Pulmon ary thromboembolism should be included among the differential diagnoses in a patient with clinical symptoms and a perfusion scan that reveals multiple branching perfusion defects.