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Soft Tissue Tumors
Pleomorphic liposarcoma
Author: Nat Pernick, M.D., PathologyOutlines.com, Inc.
Reviewer: David Lucas, M.D., University of Michigan Health Systems (January 2009)
Revised: 26 June 2009, last major update June 2009
Definition
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● Widespread high grade, pleomorphic tumor cells with some lipoblasts but no evidence of well differentiated liposarcoma
Epidemiology
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● 5% of all liposarcomas
● No gender preference
● Median age 54-70 years
● Rare in childhood
● Associated with radiation therapy or neurofibromatosis
Sites
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● Thigh (29%), internal trunk (21%), limb girdles (18%), upper extremity (16%), thoracoabdominal wall (10%)
● Often deep seated or extracompartmental
Case reports
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● 71 year old woman with tumor of foot (Diagn Pathol 2008;3:15)
● 72 year old man with epithelioid tumor (Pathol Res Pract 2004;200:545)
● Post-radiotherapy for epithelioid sarcoma (Pathol Oncol Res 2000;6:287)
Treatment and prognosis
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● Wide local excision or amputation with postoperative radiotherapy (AJSP 2004;28:1257), also chemotherapy
● Aggressive; often recurs locally (40%), metastasizes (40%), causes death (35%)
● 5 year overall survival 60%
● Poor prognostic factors: age 60+, truncal (central) location, deep, size >5 cm, vascular invasion, incomplete excision (AJSP 2002;26:601)
Gross description
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● Often large (median 8-10 cm, up to 23 cm), multinodular, white-yellow
● Usually deep (subfascial), often myxoid or necrotic areas
Gross images
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Upper arm of 87-year-old man Thigh
Other images: infiltrating gluteus muscle; retroperitoneum
Micro description
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● Well circumscribed but non-encapsulated with infiltrative borders
● At least focal typical liposarcomatous areas
● Pleomorphic cells cover > 65% of cut surface with MFH-like, round cell liposarcoma-like (without vascular network), spindle cell liposarcoma-like or epithelioid cells (Mod Path 1999;12:722)
● Usually high grade with enlarged round to bizarre nuclei; tumor necrosis common; median 25 mitotic figures/10 HPF
● May have neutrophils within giant cells, hemangiopericytic foci, extra- and intracellular hyaline droplets
Micro images
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Some lipoblasts Vacuolated lipoblasts Myxoid stroma with markedly
are present pleomorphic cells
Numerous giant lipoblasts Epithelioid variant
Pleomorphic lipoblasts Pleomorphic round cells
MFH-like areas
Markedly atypical cells
Comparison with pleomorphic Thigh tumor metastatic Varying degrees of
rhabdomyosarcoma to thyroid gland lipogenic differentiation
and signet ring cells
Cytology description
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● Pleomorphic spindle cells of high grade sarcoma with occasional lipoblasts
Positive stains
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● Vimentin, S100 (lipogenic areas in 33%), smooth muscle actin (45%), CD34, keratin (21%), desmin (13%)
Electron microscopy
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● Abundant coalescing lipid droplets, numerous cytoplasmic organelles
Molecular / cytogenetics
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● Shares similar genomic imbalances with myxofibrosarcoma (Lab Invest 2005;85:176)
● Epithelioid variant rarely has t(12;16)(q13;p11) - TLS-CHOP, more commonly seen in myxoid and round cell liposarcoma (Histopathology 2005;46:334)
Differential Diagnoses
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● Dedifferentiated liposarcoma - has well differentiated component
● MFH-pleomorphic - no definite fat vacuoles
● Pleomorphic rhabdomyosarcoma - skeletal muscle differentiation
● Metastatic carcinoma - keratin+ or other evidence of epithelial differentiation, no liposarcomatous differentiation
Additional references
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● Mod Path 2001;14:179, Stanford University
End of Soft Tissue Tumors > Pleomorphic liposarcoma of soft tissue
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