Solitary fibrous tumors Hemangiopericytoma (SFT/HP)

FACTS

  • fibroblastic mesencyhmal tumor
  • IHC: STAT6 nuclear positivity (due to NAB2–STAT6 fusion) is a diagnostic hallmark
  • pathology:
    • uniformly cellular
    • vessels: thin-walled, branching, w/ gaping sinusoidal spaces (staghorn)
  • commonly leads to mets outside of CNS
  • WHO Grades based on histologic features and mitotic activity:
Grade
Previous Terminology
Key Histologic Features
Mitotic Index (mitoses / 10 HPF)
Clinical Behavior
I
Solitary Fibrous Tumor
Patternless architecture, collagen bands, bland spindle cells
< 5
Benign, indolent
II
Hemangio-pericytoma
Increased cellularity, “staghorn” vessels, less collagen
5–9 mitoses
Intermediate, locally aggressive
III
Anaplastic Hemangio-pericytoma
Marked atypia, necrosis, high mitotic rate
≥ 10
High-grade, high recurrence/metastasis risk

HPI

universal ROS
  • cancer history

PHYSICAL EXAM

universal exam

IMAGING

well-circumscribed lesion with homogenous enhancement
A/P
Surgery is first line with adj-XRT for grade II-III, chemo for mets/recurrent tumors
Prognosis
  • Grade I: often curable with resection.
  • Grade II/III: require adjuvant radiotherapy and long-term surveillance.