Undifferentiated Pleomorphic Sarcoma
Synonyms: UPS, Malignant Fibrous histiocytoma (historical), MFH
Diagnosis of exclusion - must rule out specific sarcoma subtypes
Quick Facts
Behaviour
Malignant
Category
Soft tissue
Grade
High
Synonyms
- UPS
- Malignant Fibrous histiocytoma (historical)
- MFH
Category
Soft tissue
Behaviour
Malignant
Grade
High
Gender
Male
Tissue of Origin
No identifiable cell line
Epidemiology
- One of the most common soft tissue sarcomas in adults
- Peak incidence 50-70 years
- Can be radiation-associated
Clinical Features
- Rapidly enlarging deep soft tissue mass
- Often >5cm at presentation
- Pain in 50%
- May present with metastatic disease (lung most common)
Location
- Lower extremity (especially thigh)
- Upper extremity
- Retroperitoneum
- Trunk
Imaging
- MRI: heterogeneous solid mass with areas of necrosis/haemorrhage
- Enhancement is heterogeneous
- Often deep to fascia
Pathology
- Diagnosis of exclusion - High-grade pleomorphic sarcoma NOS
- No identifiable line of differentiation
- Marked pleomorphism, atypical mitoses
- Must exclude dedifferentiated liposarcoma (MDM2-), leiomyosarcoma, etc.
Genetics
- Complex karyotype, no specific recurrent translocation
- Must exclude MDM2 amplification (dedifferentiated liposarcoma)
Treatment
- Wide surgical excision with adequate margins
- Neoadjuvant/adjuvant radiotherapy for high-grade, deep, >5cm tumours
- Consider adjuvant chemotherapy (doxorubicin-based) for high-risk tumours
Prognosis
- 5-year survival 50-65%
- Size >5cm, deep location, high grade = adverse factors
- Metastasis rate 30-40% (predominantly lung)
- Local recurrence 20-30%
Key Points
- Diagnosis of exclusion - must rule out specific sarcoma subtypes
- Previously called Malignant Fibrous histiocytoma (MFH)
- Always exclude MDM2 amplification to rule out dedifferentiated liposarcoma
- Managed with wide excision ± radiotherapy ± chemotherapy
Workup - Blood Tests
- FBC, U&E, LFTs, Bone profile (if Bone) - baseline and pre-chemotherapy
- LDH - elevated in advanced disease
Workup - Local Imaging
MRI primary site with gadolinium
Workup - Biopsy
Core needle biopsy at sarcoma centre
Workup - Staging
- CT chest/abdomen/pelvis
- PET-CT
Workup - Other
MDM discussion at a sarcoma centre
Follow-up Summary
Soft Tissue Tumours - Localised Extremity - Intermediate and High Grade
Radiotherapy patients
monitor irradiated field for late effects at each review
Medical disclaimer
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