[398] Dedifferentiated Liposarcoma and Pleomorphic Liposarcoma: A Comparative Study on FNA Cytomorphology and MDM2/CDK4 Expression

Adrian Marino-Enriquez, Jason L Hornick, Edmund S Cibas, Xiaohua Qian. Brigham and Women's Hospital, Harvard Medical School, Boston, MA

Background: Both dedifferentiated liposarcoma (DDLPS) and pleomorphic liposarcoma (PLPS) are high-grade liposarcomas. DDLPS is a non-lipogenic sarcoma evolving from a well-differentiated liposarcoma and is characterized by amplification of MDM2 and CDK4. PLPS is a high-grade sarcoma containing lipoblasts, characterized by a complex karyotype and a more aggressive clinical course. Rarely, DDLPS shows lipogenic differentiation, mimicking PLPS. Cytomorphologic features of DDLPS and PLPS are poorly characterized.
Design: Cytologic preparations of 24 DDLPS and 14 PLPS, histologically confirmed, were retrospectively reviewed. Cytomorphologic findings were correlated with clinical, histologic and genetic data. Immunohistochemistry for MDM2 and CDK4 was performed on cell blocks and/or core needle biopsies.
Results: FNA smears from both DDLPS and PLPS were variably cellular, composed mostly of loose cellular clusters, some with abundant myxoid stroma and/or branching curvilinear vessels. Tumors were predominantly composed of spindled (21 cases), epithelioid (11), or pleomorphic (6) atypical cells, with delicate fibrillary cytoplasm and variably shaped nuclei. Additional non-distinctive features included necrosis (11), mitoses (6), or a prominent inflammatory infiltrate (8). The main cytologic difference was the presence of abundant lipoblasts and cells with microvacuolated cytoplasm in most PLPS. Multinucleated giant cells and pleomorphic cells with bizarre nuclei were present in both tumor types, but more commonly in PLPS. Extracellular hyaline eosinophilic globules were present in 2 PLPS. Expression of MDM2 and CDK4 was detected in 23 (96%) and 20 (83%) DDLPS, but in none of the PLPS except for 1 case showing weak CDK4 reactivity. Clinical features and cytogenetic data also varied between DDLPS and PLPS. All these features are summarized in Table 1.
Table 1: Clinical, cytologic, immunohistochemical, and genetic features of DDLPS and PLPS.


Conclusions: DDLPS and PLPS exhibit variable and often overlapping cytologic features. The presence of lipoblasts and cells with microvacuolated cytoplasm is more suggestive of PLPS, but can occur in DDLPS. Coexpression of MDM2 and CDK4 distinguishes DDLPS from PLPS.
Category: Cytopathology

Tuesday, March 5, 2013 1:00 PM

Poster Session IV # 82, Tuesday Afternoon

 

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