Transformation of Benign Giant Cell Tumor of Bone Into Epithelioid Angiosarcoma.

In this article, we report a case of transformation of a benign giant cell tumor (GCT) of the calcaneus into an epithelioid angiosarcoma. The patient presented to our service in 2003 and was followed until 2014. Transformation occurred 11 years after curettage, cryotherapy, cementation, and a well-documented disease-free interval. Longitudinal radiographs, magnetic resonance imaging, and histopathology were evaluated by the same medical team. There are only a few case reports and case series of malignancy associated with GCT of bone. To our knowledge, this case report is the first to describe an assessment of the transformation of a benign GCT of bone into an epithelioid angiosarcoma. Orthopedic surgeons, radiologists, oncologists, and pathologists should be aware of the potential for transformation of benign GCTs to high-grade sarcomas after a long disease-free interval.