Case report: two-step malignant transformation of a liposclerosing myxofibrous tumor of bone.

We present the case of a patient with malignant transformation of a liposclerosing myxofibrous tumor. The patient had a histologically confirmed liposclerosing myxofibrous tumor that, during a course of 22 months, spontaneously transformed into a lesion appearing like a benign giant cell reactive lesion and subsequently into a high-grade bone sarcoma. Few such cases of spontaneous malignant transformation of liposclerosing myxofibrous tumor have been reported. We report what we believe to be the first case documenting spontaneous transformation of a liposclerosing myxofibrous tumor into an intermediate lesion with benign-appearing histologic features and then into a high-grade malignant tumor.