Table of Contents
Definition / general | Terminology | Epidemiology | Sites | Case reports | Treatment | Gross images | Microscopic (histologic) description | Microscopic (histologic) images | Cytology description | Positive stains | Electron microscopy description | Differential diagnosisCite this page: Well differentiated myxoid liposarcoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/softtissueadiposemyxoidlipowd.html. Accessed January 17th, 2021.
Definition / general
- 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, very rarely in elderly
Sites
- Usually thigh and lower extremity of young adults
- Retroperitoneal involvement is rare
Case reports
- 71 year old man with supraclavicular fossa mass (Chest 2000;117:1518)
- Young men with multicentric tumors (World J Surg Oncol 2007;5:139)
Treatment
- 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
Images hosted on PathOut servers:
Well differentiated myxoid liposarcoma
Images hosted on other servers:
Recurrence of the adipose mass with kidney involvement
Well circumscribed white tumor
Lobulated gray-white tumor within skeletal muscle
Microscopic (histologic) 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
Microscopic (histologic) images
Images hosted on PathOut servers:
Lipoblasts, myxoid stroma and branched capillaries
Cords of cells resembling myxoid chondrosarcoma
Resembles pulmonary edema due to large irregular cystic spaces, some with granular eosinophilic material
Hyalinized collagenous stroma (rare finding)
Large (mature) and small fat cells
Hypocellular zones: left-small artery, middle-veins, right-transition between cellular and hypocellular areas
Signet ring lipoblasts
Images hosted on other servers:
Lipoblasts, myxoid stroma and branched capillaries
Metastases
Lipoblasts, myxoid stroma and branched capillaries
Lipoblasts
Cytology description
- Myxoid material with arborizing blood vessels and lipoblasts (Acta Cytol 2007;51:456)
Positive stains
Electron microscopy description
- White adipose tissue, aggregates of 60-Angstrom intermediate filaments and large masses of glycogen (Am J Clin Pathol 1979;72:521)
- Cells have investing basal lamina, pinocytotic vesicles, cytoplasmic glycogen and cytoplasmic lipid (Am J Surg Pathol 1980;4:163)
- Resembles lipoblastoma
Differential diagnosis
- Extraskeletal myxoid chondrosarcoma: malignant chondrocytes, no cytoplasmic fat vacuoles, no prominent vasculature
- Lipoblastoma / lipoblastomatosis: 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
