Home   Chapter Home   Jobs   Conferences   Fellowships   Books

 

 

 

 

Soft Tissue Tumors

Well differentiated myxoid liposarcoma

 

Author: Nat Pernick, M.D., PathologyOutlines.com, Inc.

Reviewer: David Lucas, M.D., University of Michigan Health Systems (January 2009)

Revised: 17 June 2009, last major update June 2009

 

Definition

=========================================================================

● Low grade tumor with primitive non-lipogenic mesenchymal cells, signet ring lipoblasts and prominent myxoid stroma with branching vascular pattern

 

Terminology

=========================================================================

● Also called paucicellular myxoid liposarcoma

 

Epidemiology

=========================================================================

● Peaks in 30’s and 40’s

● May occur in children

 

Sites

=========================================================================

● Usually thigh and lower extremity of young adults

● Retroperitoneal involvement is rare

 

Case reports

=========================================================================

● Young men with multicentric tumors (World J Surg Oncol 2007;5:139)

 

Treatment and prognosis

=========================================================================

● Median survival 105 months (Ann Surg Oncol 2007;14:1507)

● Pure tumors (without round cells) have low grade behavior with only rare metastases

● Poorer prognosis if round or pleomorphic cells

 

Gross images

=========================================================================

 

                                                    

Gelatinous cut surface                     Tumor of popliteal region                                 Distal thigh tumor of

(M-myxoid, arrow-adipose)                             16-year-old boy

 

 

57-year-old man with cyst-like

tumor in subcutis of thigh

 

Other images: well circumscribed white tumorlobulated gray-white tumor within skeletal muscle

 

Micro description

=========================================================================

● Low grade and paucicellular with monomorphic, stellate or fusiform cells without atypia

● Prominent chicken wire vasculature (delicate thin walled arborizing and curving capillaries)

● Numerous signet ring lipoblasts, particularly at periphery of lobules, has mucoid matrix rich in hyaluronidase sensitive acid mucopolysaccharides, may have large mucoid pools

● Lymphangioma-like cystic degeneration is relatively specific; rarely metaplastic cartilage or cartilage with TLS-CHOP fusion gene (Appl Immunohistochem Mol Morphol 2007;15:477)

● No/rare mitotic figures

 

Micro images

=========================================================================

 

                                                                           

Small back to back fat cells            Large (mature) and                             

                                                                small fat cells                                     

 

 

                                                           

Resembles pulmonary edema        Large irregular cystic spaces        Cystic spaces with granular

                                                                                                                                eosinophilic material

 

 

                                                                                 

Hypocellular around                          Large hypocellular zones                 Transition between cellular

a small artery                                      around veins                                        and hypocellular areas

 

 

                                        

Cords of cells resembling                Hyalinized collagenous stroma (rare)

myxoid chondrosarcoma

 

 

                    

Lipoblasts, myxoid stroma and branched capillaries

 

 

                              

Lipoblasts, myxoid stroma and branched capillaries

 

 

                       

Signet ring lipoblasts       

 

 

                    

Metastases to  heart                         Metastases to thoracic epidural space

 

Other images: lipoblasts, myxoid stroma and branched capillaries #1#2#3lipoblasts #1#2#3#4

 

Cytology description

=========================================================================

● Myxoid material with arborizing blood vessels and lipoblasts (Acta Cytol 2007;51:456)

 

Positive stains

=========================================================================

● Vimentin, S100, CD36 (AJCP 1995;103:20)

 

Electron microscopy

=========================================================================

● White adipose tissue, aggregates of 60-Angstrom intermediate filaments and large masses of glycogen (AJCP 1979;72:521)

● Cells have investing basal lamina, pinocytotic vesicles, cytoplasmic glycogen and cytoplasmic lipid (AJSP 1980;4:163)

● Resembles lipoblastoma

 

Differential diagnosis

=========================================================================

● Extraskeletal myxoid chondrosarcoma - malignant chondrocytes, no cytoplasmic fat vacuoles, no prominent vasculature

● Lipoblastoma - similar histology but age 5 years or less

● Myxofibrosarcoma - older adults, often superficial, infiltrative, no cytoplasmic fat vacuoles, more nuclear atypia, thicker curvilinear vessels, frequent mitotic figures

● Myxoma - extremely paucicellular, lacks a prominent vascular component

 

End of Soft Tissue Tumors >  Well differentiated myxoid liposarcoma

 

 

 

This information is intended for physicians and related personnel, who understand that medical information is often imperfect, and must also be interpreted in the context of a patient's clinical data using reasonable medical judgment.  This website should not be used as a substitute for the advice of a licensed physician.

 

All information on this website is protected by Copyright, (c) 2001-2009, PathologyOutlines.com, Inc.  Information from third parties may also be protected by copyright.  Please contact us at copyrightPathOut@gmail.com with any questions.