Malignant Fibrous Histiocytoma
Synonyms: MFH, undifferentiated pleomorphic sarcoma
Now considered largely synonymous with undifferentiated pleomorphic sarcoma per WHO 2020
Quick Facts
Behaviour
Malignant
Category
Bone and soft tissue
Grade
High
Synonyms
- MFH
- undifferentiated pleomorphic sarcoma
Category
Bone and soft tissue
Behaviour
Malignant
Grade
High
Gender
Male
Tissue of Origin
Fibrous
Epidemiology
- Now largely reclassified as undifferentiated pleomorphic sarcoma (UPS)
- Peak incidence in 5th–7th decades
- Slight Male predominance
- May arise de novo or secondary to prior irradiation or Bone infarct
Clinical Features
- Painful enlarging mass
- Rapid growth
- Pathological fracture common in Bone MFH
- Constitutional symptoms (weight loss, fatigue) in advanced disease
Location
- Metaphysis of long bones (distal femur, proximal tibia) for Bone MFH
- Extremities (thigh most common) for soft tissue MFH
- Retroperitoneum
Imaging
- Aggressive permeative lytic lesion with cortical destruction
- Soft tissue mass extension common
- No tumour matrix mineralisation
- MRI: heterogeneous signal with areas of necrosis
Pathology
- High-grade pleomorphic spindle cell sarcoma
- Storiform growth pattern with marked nuclear atypia
- Numerous atypical mitoses
- Areas of necrosis common
Genetics
- Complex karyotype with multiple chromosomal gains and losses
- No specific defining mutation
- MDM2 amplification may be present
Treatment
- Wide surgical resection with negative margins
- Neoadjuvant and adjuvant chemotherapy (doxorubicin/ifosfamide-based)
- Radiotherapy for unresectable or margin-positive disease
Prognosis
- 5-year survival approximately 50–60% for localised disease
- Metastasis to lungs in 40% of cases
- Poor prognosis with positive margins or metastatic disease
Key Points
- Now considered largely synonymous with undifferentiated pleomorphic sarcoma per WHO 2020
- Must rule out other pleomorphic sarcomas with differentiation (dedifferentiated liposarcoma, etc.)
- MDM2 FISH and immunohistochemistry helpful to exclude dedifferentiated liposarcoma
Workup - Blood Tests
- FBC, U&E, LFTs, Bone profile (if Bone) - baseline and pre-chemotherapy
- LDH - elevated in advanced disease
- Coagulation screen - pre-operative
Workup - Local Imaging
- Plain radiograph (Bone MFH)
- MRI primary site with gadolinium
Workup - Biopsy
- Core needle biopsy at sarcoma centre - en bloc excision of tract
- Histology: storiform pleomorphic sarcoma with High-grade atypia
- Comprehensive IHC + molecular testing to exclude other pleomorphic sarcomas (DDLPS, pleomorphic liposarcoma)
- MDM2 FISH - to exclude dedifferentiated liposarcoma
Workup - Staging
- CT chest/abdomen/pelvis - pulmonary and visceral metastases
- PET-CT - increasingly used for staging
Follow-up Summary
- 1
Year 1
Post-operative visit within first 6 weeks; 3–4 monthly clinical examination and CXR; image prosthesis at 6 months and 1 year
- 2
Year 2
3–4 monthly clinical examination and CXR; image prosthesis annually
- 3
Years 3–4
6-monthly clinical examination and CXR; image prosthesis annually
- 4
Years 5–10
Annual clinical examination and CXR; image prosthesis annually
- 5
Discharge at 10 years after surgery
Medical disclaimer
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