[484] Cutaneous Pleomorphic Liposarcoma (PL): A Clinicopathologic Study of 33 Cases with Evaluation of MDM2 Gene Amplification in 19.

Jerad M Gardner, Monisha Dandekar, Dafydd G Thomas, John R Goldblum, Sharon W Weiss, Steven Billings, David R Lucas, Jonathan B McHugh, Rajiv M Patel. Emory University, Atlanta, GA; University of Michigan, Ann Arbor; Cleveland Clinic, OH

Background: PL is a rare form of liposarcoma which rarely occurs in the skin where its behavior is incompletely defined. MDM2 gene amplification in a limited number of recent PLs suggests it may be part of the spectrum of well differentiated liposarcoma/dedifferentiated liposarcoma (WDL/DL) rather than a distinct subtype, but this finding has not been extended to a large group of tumors.
Design: PL involving dermis and/or subcutis were obtained from institutional and consultation files (n=33). Cases were evaluated with respect to age, sex, location (dermis [D], dermis and subcutis [DS], subcutis [S]), size, predominant pattern (pleomorphic spindled vs. epithelioid), amount of lipogenic differentiation, and tumor necrosis. MDM2 amplification was analyzed by FISH on formalin fixed paraffin embedded material in 19 cases.
Results: Patients ranged in age from 5-93 years (M:F=1.5:1). Tumors were located on the extremity (n=18), trunk (n=8), and head and neck (n=7) and involved the D (n=6), DS (n=9) and S (n=18). Tumor size ranged from 0.8 to 15 cm (median: 2 cm). All were mitotically active high grade sarcomas with either a pleomorphic spindled (n=26) or an epithelioid pattern (n=7) with a variable amount of lipogenic differentiation (<25% [n=15], 25%-50% [n=8], >50% [n=10]). Necrosis was present in some cases (n=5). MDM2 gene amplification was present in 3 of 19 cases. Follow up information in 20 cases (range= 1-192 mos; median= 52 mos; mean= 62 mos) disclosed local recurrences (2/20) but no metastasis or death from disease.
Conclusions: We conclude that 1. Cutaneous PLs, despite their high grade, have an excellent outcome attributed to their small size and superficial location. 2. The low incidence of MDM2 gene amplification indicates that not all PLs are related to WDL/DL. 3. PLs may, therefore, represent a group of sarcomas evolving by way of more than one molecular pathway.
Category: Dermatopathology

Wednesday, March 2, 2011 1:00 PM

Poster Session VI # 124, Wednesday Afternoon


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