Differential Diagnosis
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).
Lipomatous Hemangiopericytoma
Dedifferentiated Liposarcoma
Cytologically bland
High grade dedifferentiated areas
No areas of atypical lipomatous tumor
Areas or history of atypical lipomatous tumor
Circumscribed
Usually non-circumscribed
Independently Arising Nono-lipogenic Sarcoma vs Atypical Lipomatous Tumor
Must be ruled out by adequate pathologic and surgical sampling
There should be a high level of suspicion for tumors arising in the retroperitoneum
Prior specimens should be examined
Radiographic evidence should be sought of a non-sampled fatty component
MDM2
CDK4
Dedifferentiated Liposarcoma
95%
92%
MFH
11
3
Myxofibrosarcoma
42
17
Leiomyosarcoma
6
1
Maligant peripheral nerve sheath tumor
64
12
Dedifferentiated Liposarcoma GIST
Frequently markedly pleomorphic
Pleomorphism infrequent, even in malignant lesions
CD117, DOG1 negative
CD117, DOG1 85-95%
CD34 may be positive in both
