Hemangiopericytoma

 

Epidemiology:

    • Middle aged women commonly

 

Common sites:

    • pelvic retroperitoneum
    • lower extremities (esp thigh)

 

Gross features:

    • fleshy or spongy
    • 5-15cm

 

Histologic features:

    • resembles cellular areas of solitary fibrous tumour
    • thin-walled “staghorn” branching vessels
    • features associated with aggressive behaviour:
      • necrosis
      • high mitotic rate
      • nuclear pleomorphism
      • size >5cm
    • lipomatous hemangiopericytoma:
      • almost non-recurring, non-metastasizing
      • mature adipocytes and hemangiopericytoma-like areas
      • well-demarcated
      • varying combination of patternless cellular areas, prominent hemangiopericytoma-like vessels, variably collagenized extracellular matrix, and lipomatous areas
      • CD99 + consistently
      • CD34 + (75%)
      • Bcl2+ (60%)

 

Immunophenotype:

Marker:

Sensitivity:

Specificity:

CD34 

 

 

Reticulin

 

 

SMA (neg)

 

 

 

Molecular features:

    •  

 

Other features:

    • diagnosis is falling out of favour of solitary fibrous tumour and other entities
    • One third are malignant
    • Not arising from pericytes

 

References:

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