A high grade sarcoma arising in a location typical of atypical lipomatous tumor (such as retroperitoneum) that is FISH positive for amplification of MDM2 may also be considered a dedifferentiated liposarcoma
Metastases contain only the high grade sarcoma component
By definition, may not occur following radiation of atypical lipomatous tumor
Low grade dedifferentiated liposarcoma has been proposed
Classically, pleomorphic liposarcoma was not permitted as the dedifferentiated component, but it appears that it rarely occurs in this guise, associated with atypical lipomatous tumor and expressing MDM2
(see Boland 2010).
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