Synonyms

Hemangiopericytoma (now reclassified as SFT)

Category

Soft tissue

Behaviour

Intermediate

Grade

Variable

Gender

Both equally

Tissue of Origin

Fibrous

Epidemiology

• Intermediate-grade mesenchymal tumour
• Peak incidence 4th-6th decades
• Can occur in various sites
• NAB2-STAT6 fusion characteristic

Clinical Features

• Often asymptomatic incidental finding
• Slow-growing
• Larger lesions may cause mass effect
• Hypoglycaemia if large (paraneoplastic)

Location

• Soft tissues (extremities, trunk)
• Pleura and lung
• Meninges
• Liver
• Orbit

Imaging

• MRI: homogeneous or heterogeneous
• T1 isointense, Variable T2
• Well-demarcated
• Significant Vascularity possible

Pathology

• Bland spindle cells in fascicles or storiform pattern
• Prominent branching haemangiopericytoma-like vasculature
• NAB2-STAT6 fusion confirmatory
• STAT6+ on immunostain

Genetics

NAB2-STAT6 fusion 90%

Treatment

• Wide surgical excision: primary treatment
• Risk assessment important (size, mitotic rate)
• Adjuvant radiotherapy: High-risk lesions
• Chemotherapy/VEGF inhibitors: for unresectable or progressive

Prognosis

• Variable based on risk: Low-risk excellent, High-risk 50-60% 5-year
• Recurrence and metastasis possible especially High-risk

Key Points

• Intermediate-grade with Variable behaviour
• Risk assessment scheme guides treatment
• NAB2-STAT6 fusion diagnostic

Workup - Blood Tests

Glucose: screen for hypoglycaemia

Workup - Local Imaging

• MRI primary site: assess size and extent
• CT chest/abdomen: baseline for High-risk

Workup - Biopsy

STAT6 immunostain: NAB2-STAT6 fusion indicator

Workup - Staging

No standard staging