Dedifferentiated Liposarcoma
Synonyms: DDLPS, high-grade liposarcoma
High-grade liposarcoma with a mixture of well differentiated regions and non-lipogenic spindle cell or pleomorphic sarcoma
Quick Facts
Behaviour
Malignant
Category
Soft tissue
Grade
High
Synonyms
- DDLPS
- high-grade liposarcoma
Category
Soft tissue
Behaviour
Malignant
Grade
High
Gender
Male
Tissue of Origin
Adipose
Epidemiology
- 20% of all liposarcomas
- Peak incidence in 6th-7th decades
- Can arise de novo or from well-differentiated liposarcoma
Clinical Features
- Large, often painless retroperitoneal mass
- Abdominal discomfort, constipation, urinary symptoms
- Peripheral extremity form: large deep soft tissue mass
- Weight loss and fatigue with large tumours
Location
- Retroperitoneum (75%)
- Deep extremity (thigh)
- Spermatic cord (paratesticular)
- Other deep sites
Imaging
- MRI: Large heterogeneous mass with fatty and non-fatty components
- Fat-containing well-differentiated component adjacent to non-fatty dedifferentiated nodule
- CT: Adipose density component + solid enhancing mass
Pathology
- Non-adipocytic high-grade sarcoma (resembling MFH/UPS or myxofibrosarcoma) adjacent to well-differentiated liposarcoma
- Abrupt transition between components
Genetics
- MDM2 amplification - present in >95% (also in WDLPS/ALT)
- CDK4 amplification - co-amplified with MDM2
- FISH for MDM2 is gold-standard confirmation
- 12q13-15 amplification (supernumerary ring or giant marker chromosomes)
Treatment
- Wide surgical resection - often challenging in retroperitoneum
- Radiotherapy
- Re-resection for recurrence
- Chemotherapy controversial
- CDK4/6 and MDM2 inhibitors - clinical trials ongoing
Prognosis
- 5-year survival 40-50%
- High local recurrence rate in retroperitoneum (40-60%)
- Distant metastasis in 20-30%
- Retroperitoneal location associated with worse prognosis than extremity
Key Points
- High-grade liposarcoma with a mixture of well differentiated regions and non-lipogenic spindle cell or pleomorphic sarcoma
- MDM2 amplification
- High rate of local recurrence as well as metastatic disease to lungs
Workup - Blood Tests
- FBC, U&E, LFTs - pre-operative and pre-systemic therapy baseline
- LDH
Workup - Local Imaging
- CT chest/abdomen/pelvis - retroperitoneal cases
- MRI with contrast primary site - better soft tissue characterisation; identifies transition to dedifferentiated component
Workup - Biopsy
Core needle biopsy - must sample non-fatty (dedifferentiated) component
Workup - Staging
- CT chest/abdomen/pelvis - metastases (20-30% at presentation in high-grade disease)
- CT abdomen essential for retroperitoneal primary to assess organ involvement
Workup - Other
MDM discussion at a sarcoma centre
Follow-up Summary
Medical disclaimer
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