A case of pulmonary metastasis of giant cell tumor of bone presenting as pulmonary arteriovenous malformation.

Although giant-cell tumor (GCT) of the bone was originally classified as a benign tumor, metastasis has been reported. The radiographic features usually comprise parenchymal solitary or multiple nodules that are round-to-oval nodular opacities of homogeneous density in patients with GCT. However, the patient described in this case presented with a hypervascular mass with feeding vessels and hemothorax, which are common features of pulmonary arteriovenous malformation. To the best of our knowledge, cases of pulmonary metastases presenting as a pulmonary arteriovenous malformation have not been reported. Here, we report a case of giant-cell tumor of the bone that exhibited histologically benign pulmonary metastases and mimicked an arteriovenous malformation.