[67] Dedifferentiated Liposarcoma of the Extremities: Relative Incidence Compared with Atypical Lipomatous Tumors of the Extremities, and Clinicopathologic Features Including Two Cases with Morphology of So-Called "Inflammatory MFH"

Samuel Reynolds, David Meredith, Francine Leech, Robert Quinn, Berndt Schmit, Therese Bocklage. University of New Mexico SOM, Albuquerque, NM; UNM SOM, Albuquerque, NM

Background: Dedifferentiated liposarcoma (DDLPS) is reportedly rare in the extremities compared with retroperitoneum. Advances in identification through IHC for the proteins, CDK4 and MDM2, may increase recognition of these tumors when occuring in the extremities exclusively as sarcoma, NOS. Accurate diagnoses is crucial because of improved prognosis compared with sarcoma, NOS.
Design: The Pathology database was searched for non-retroperitoneal ALT and liposarcomas for 2001 to 2011. Clinical, radiologic, and pathologic features were evaluated. Radiology and pathology reports were reviewed, and scans and slides were re-examined. The relative frequency of DDLPS was compared with ALT.
Results: Table One lists pure ALT, mixed ALT/DDLPS and pure DDLPS.

Non-Retroperitoneal DDLPS and ALT
AVERAGE AGE62.6 years70 years61 years
GENDER18 F, 20 M2 F, 6 M2 F, 6 M
AVERAGE SIZE18.312.410
LOCATION30 E, 5 T, 2 each H&N and G8 E6 E, 2 T
F = female, M = male, Size is in centimeters E= Extremities, T= Trunk, G= Groin, H&N= head and neck

Thirty percent of non-retroperitoneal liposarcomas consisted of dedifferentiated LPS eight of which were mixed ALT/DDLPS and eight pure DDLPS. Only one patient progressed from ALT to DDLPS. Dedifferentiated components included two cases of "inflammatory MFH", one case with myofibroblastic differentiation, one case mimicking sclerosing epithelioid fibrosarcoma, two cases simulating adult type fibrosarcoma, three cases with the appearance of an epithelioid sarcoma (INI-1 intact), and the remaining dedifferentiated components consisted of high grade pleomorphic undifferentiated sarcoma (n = 7). There was no difference in patient age or tumor size. Males outnumbered females by 3:1 for dedifferentation. Radiology supported low grade fatty tumor for the pure ALT or predominantly pure ALT, and suggested DDLPS for a few of the mixed DDLPS cases, while the pure DDLPS cases were interpreted as suspicious for high grade sarcoma. For pure DDLPS, CDK4, MDM2 and/or karyotypes supported the diagnosis.
Conclusions: Dedifferentiated liposarcoma may become increasingly recognized as in non-visceral soft tissues due to CDK4 and MDM2 immunohistochemistry. The range of morphologies in the extremities includes the "inflammatory MFH" like pattern noted in retroperitoneal DDLPS.
Category: Bone & Soft Tissue

Monday, March 19, 2012 1:00 PM

Poster Session II # 9, Monday Afternoon


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