Solitary fibrous tumour

Solitary fibrous tumour, abbreviated SFT, is a type of soft tissue tumour that fits in the fibroblastic/myofibroblastic tumours. It is usually benign.

Solitary fibrous tumour
Diagnosis in short
Solitary fibrous tumour. H&E stain.
LM	spindle cells in a patternless pattern, hemangiopericytoma-like areas (staghorn vessels), keloid-like collagen bundles, +/-well-circumscribed (common)
Subtypes	benign (common), malignant (uncommon)
IHC	CD34 ~90% +ve, CD99 ~70% +ve, BCL2 ~50% +ve
Site	soft tissue - fibroblastic/myofibroblastic tumours, pleura
Syndromes	Doege-Potter syndrome
Prognosis	usu. good

SFT of the pleura is dealt with in a separate article solitary fibrous tumour of the pleura.

General

• Grouped with hemangiopericytoma in the WHO classification - as it is thought to be the same tumour.
• May be benign or malignant; more commonly benign.
• May be associated with hypoglycemia.
  • Known as Doege-Potter syndrome.

Gross

• Soft tissue mass.

Microscopic

Features - benign:

• Spindle cells in a patternless pattern.
• Hemangiopericytoma-like area (staghorn vessels).
• Keloid-like collagen bundles - key feature.
• +/-Well-circumscribed (common).

Criteria for malignancy:

• Necrosis.
• Mitoses >4/10 HPF -- definition suffers from HPFitis.
• Increased cellularity.
• Marked nuclear atypia.
• Infiltrative margin.

Images

• 

  Benign SFT - low mag. (WC)

• 

  Benign SFT - intermed. mag. (WC)

• 

  Benign SFT - high mag. (WC)

www:

• SFT of the brain - several images (upmc.edu).

IHC

• CD34 ~90% +ve.
• CD99 ~70% +ve.
• BCL2 ~50% +ve.

See also

• Fibroblastic/myofibroblastic tumours.