Chronic solitary pulmonary nodule due to unsuspected pulmonary infarction from silent pulmonary embolism

A case of pulmonary embolism showing a longstanding solitary pulmonary nodule is presented. An asymptomatic 57 year-old man with a solitary nodule in the right lower lobe was referred to our hospital. A pulmonary perfusion-ventilation scan following a sudden onset of dyspnoea established the diagnosis of recurrent pulmonary embolism. The nodule gradually disappeared after anticoagulant treatment, indicating that the nodule was pulmonary infarction from silent pulmonary embolism. Although the incidence of pulmonary infarction is low in Japan, this case suggests that pulmonary infarction from silent pulmonary embolism should be considered as one important cause of a solitary pulmonary nodule.