[20] Metastasizing Dedifferentiated Liposarcoma: Clinical and Morphologic Analysis.

Tariq J Al-Zaid, Markus Ghadimi, Tingsheng Peng, Chiara Colombo, Keila E Torres, Dina Lev, Alexander J Lazar. UT-MD Anderson Cancer Center, Houston, TX

Background: Dedifferentiated liposarcoma consists of well differentiated (WD) liposarcoma with a dedifferentiated (DD) higher grade, non-lipogenic component. The majority of fatal cases are attributed to local aggressiveness. The incidence of distant metastasis reported in the literature is relatively low (1-18%) for retroperitoneal cases and predicts a rapidly fatal course.
Design: Patients with DD liposarcoma who developed distant metastasis (n=45) were identified in our liposarcoma database (total, n=491; de novo DD, n=197; secondary DD, n=62; WD only, n=232). H&E slides for 21 patients were available (remaining 24 are being acquired). A metastasis was defined as tumor involving a distinct, distant site. The dominant morphologic patterns of the DD component was classified as: myxofibrosarcoma(MFS)-like, malignant fibrous histiocytoma/pleomorphic undifferentiated sarcoma (MFH/UPS)-like, pleomorphic liposarcoma(PLS)-like, sarcoma with heterologous elements, pure pleomorphic, and epithelioid. The primary/recurrent DD component was graded per FNCLCC criteria. The highest grade observed from a primary/recurrent tumor from each patient was used for analysis.
Results: Patient age at primary liposarcoma diagnosis was 33 to 78 years including males (n=32) and females (n=13). Primary tumors were retroperitoneal (n=31; 69%), scrotal (n=4; 9%), pelvic/mesenteric (n=4; 9%), chest/abdominal wall (n=5; 11%), and mediastinal (n=1; 2%). 42 cases arose from de novo DD and 3 from secondary DD. The sites of metastasis include lung (n=34; 76%), liver (n=11; 24%), bone (n=3; 7%), brain (n=2; 4%), and other (n=3; 7%). Metastasis to more than one organ were present in 12 patients (27%). Of the 21 patients with histologic slides available, the DD component exhibited the following morphologic patterns (often multiple) in the primary tumor or recurrence: MFH/UPS-like (n=15; 72%), MFS-like (n=8; 38%), heterologus element osteosarcoma (n=3; 14%), pure pleomorphic (n=1; 5%). The DD component was FNCLCC high grade (n=2; 10%) or intermediate (n=19; 90%).
Conclusions: In our series, most metastases from DD liposarcoma originated from retroperitoneum (69%; the most prevalent primary site), scrotum (9%) and chest/abdominal wall (11%). The most common metastatic sites were lung (76%) and liver (24%). The prevalent primary/recurrent DD component morphology was MFH/UPS-like (72%) followed by MFS-like (38%); most metastases arose from DD graded FNCLCC intermediate. The overall metastatic rate for DD liposarcoma was 17% (21% of de novo DD; 5% of secondary DD).
Category: Bone & Soft Tissue

Tuesday, March 1, 2011 2:00 PM

Platform Session: Section E, Tuesday Afternoon


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