Hemangiopericytoma
Epidemiology:
- Middle aged women
commonly
Common sites:
- pelvic retroperitoneum
- lower extremities
(esp thigh)
Gross features:
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:
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Sensitivity:
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Specificity:
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CD34
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Reticulin
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SMA (neg)
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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: