Management of Solitary Fibrous Tumour by Anatomical Location
Primary Treatment Principle
Complete surgical resection with negative margins is the definitive treatment for solitary fibrous tumours at all anatomical locations, and should be performed by a surgeon with sarcoma expertise at a specialist sarcoma multidisciplinary team (MDT) center. 1, 2
Location-Specific Management Algorithms
Extremity and Superficial Trunk SFTs
- Surgical approach: Excise the tumour with a margin of normal tissue, guided by anatomical location and functional consequences of resection 1
- Margin strategy: Close or planned microscopic positive margins off critical structures are acceptable when supplemented with neo/adjuvant radiotherapy, achieving low local recurrence rates 1
- Radiotherapy benefit: SFTs are among the histological types that gain the greatest benefit from radiotherapy 1
- Plastic reconstruction: Should be utilized as needed and coordinated with timing of radiotherapy 1
Retroperitoneal SFTs
- Pre-biopsy referral: Any retroperitoneal or intra-abdominal mass with imaging suggestive of soft tissue sarcoma must be referred to a specialist MDT before biopsy or surgical treatment 1
- Surgical goal: Complete resection with negative margins while preserving uninvolved organs, as retroperitoneal SFTs have low risk of local recurrence 3, 2
- Resection technique: En-bloc removal with any adherent structures, even if not overtly infiltrated, to achieve macroscopically complete resection 2
- Avoid incomplete resection: Grossly incomplete resection offers questionable benefit and may be harmful 2
- Neoadjuvant radiotherapy: Often preferred (45-50 Gy) as it reduces tumour seeding risk and may improve resectability 3
Central Nervous System (CNS) SFTs
- Surgical standard: Gross total resection is the recommended treatment 4
- Postoperative radiotherapy: Applied selectively; was used in five of ten cases in a recent series 4
- Critical surveillance need: Lifelong follow-up is necessary due to risk of delayed recurrence (6-8 years) and distant metastases (9-13 years), even after gross-total resection 4
Head and Neck/Paravertebral SFTs
- Surgical approach: Radical excision via appropriate transcervical or site-specific approach with free margin excision 5
- Diagnostic pitfall: Core needle biopsy may not be univocal; STAT6 nuclear positivity is the surrogate marker for NAB2-STAT6 gene fusion, the specific driver mutation of SFT 5
- Adjuvant therapy: Should be contemplated in high-risk disease 5
Universal Management Principles Across All Locations
Pre-Treatment Workup
- Histopathological diagnosis: Should be made by percutaneous core biopsy reviewed by a specialist sarcoma pathologist for diagnostic confirmation and molecular analysis 1
- Primary tumour imaging: Cross-sectional imaging (usually MRI) is recommended prior to definitive surgery 1
- Metastatic screening: CT scan of thorax for lung metastases should be performed prior to radical treatment 1
- MDT review: All cases must be managed by a formally constituted sarcoma MDT, with decisions about surgery, chemotherapy, and radiotherapy made collectively 1
Surgical Principles
- Timing: Early definitive surgery offers the best chance of cure at primary presentation 2
- Margin status: Positive surgical margins predict worse local recurrence-free survival and metastasis-free survival 6
- Tumour size consideration: Tumours greater than 10 cm predict worse metastasis-free survival and warrant closer surveillance 6, 7
Radiation Therapy Considerations
- Radiation sensitivity: SFTs exhibit radiation sensitivity, which should be factored into treatment planning 1, 2
- Postoperative RT: After complete resection, provides limited benefit and carries significant toxicity; should be reserved for selected patients with a well-defined area at risk for local recurrence 2
- When RT is optional: If not given pre-operatively and further resection is not feasible 1
Inadvertent Excision Management
- Staging: Patients who underwent inadvertent surgery without preoperative diagnosis should be fully staged with MRI of the surgical bed to look for gross residual disease 1
- Re-excision decision: May be advised if adequate margins can be achieved with acceptable morbidity; however, if further surgery would result in considerable morbidity or is unlikely to achieve complete clearance, observation or radiotherapy may be alternative strategies 1
Surveillance Strategy
Imaging Protocol
- Modality: Cross-sectional imaging with MRI preferred for soft-tissue characterization 2, 4
- Intervals: Every 3-6 months initially, extending to annual after 5 years 3, 2
- Rationale: Can detect asymptomatic recurrences long before clinical symptoms appear 2
Systemic Metastasis Screening
- For CNS SFTs: CT thorax-abdomen or full body PET should be considered for detection of systemic metastases at diagnosis and during follow-up 4
- Timing: Particularly important given delayed metastasis risk (9-13 years after diagnosis) 4
Critical Pitfalls to Avoid
- Never proceed with major surgical resection before establishing diagnosis with biopsy, as this prevents inappropriate resection of lymphoma, germ cell tumours, or benign inflammatory conditions that require medical rather than surgical management 3
- Do not perform wide undermining prior to confirmation of clear margins, as this creates difficulty interpreting subsequent re-excised margins and risks concealing residual tumour below mobilized tissue 1
- Avoid grossly incomplete resection, as it offers questionable benefit and may be harmful 2
- Do not assume benign behavior based on location alone: extrathoracic SFTs have an increased risk of local recurrence compared to thoracic SFTs, though metastasis-free survival is similar 6