Influenza A infection simulating pulmonary embolism.

The diagnosis of pulmonary embolism is generally established when the patient has characteristic pulmonary perfusion abnormalities in the setting of an appropriate clinical history and with no concurrent cardiopulmonary disease on chest x-ray film. The initial evaluation, including positive pulmonary perfusion scan, of four young black women suggested the diagnosis of pulmonary emboli. A syndrome of respiratory tract viral infection then developed, and further evaluation by angiography and perfusion scans contradicted the diagnoses of pulmonary emboli. Each patient had substantial convalescent-phase complement-fixation titers to influenza A. Thus, if reliance is placed in pulmonary perfusion scans, an erroneous diagnosis of pulmonary emboli may be made for patients with influenza A.