BACKGROUND

Are hemangiopericytomas benign or malignant lesions?

Hemangiopericytomas are considered malignant lesions (sarcomatous lesions associated with blood vessels).

What is the cell of origin of hemangiopericytomas?

Hemangiopericytomas were originally thought to originate from pericytes of the smooth muscle cells of vessels but are now felt to be of fibroblastic origin.

From which other tumor is a hemangiopericytoma difficult to distinguish pathologically?

Solitary fibrous tumor (SFT). The consensus view is that solitary fibrous tumors and hemangiopericytomas belong to the same spectrum of tumors of fibroblastic origin; most hemangiopericytomas are now classified as solitary fibrous tumors (either pleural or extrapleural).

What is the most common location of solitary fibrous tumors?

The most common location is the lower extremity. Other sites include the H&N, retroperitoneum, and brain (least common). If in the brain (hemangiopericytomas), they are often meninges based.

What does the prognosis of hemangiopericytomas and solitary fibrous tumors primarily depend on?

The prognosis depends primarily on tumor location and ability to achieve gross-total resection (GTR); for example, for CNS tumors, supratentorial tumors have a better prognosis than posterior fossa and base of skull tumors.

What is the rate of local recurrence for resected CNS hemangiopericytomas?

Very high, even after gross-total resection (GTR); as high as 91% in some studies. (Guthrie BL et al., Neurosurgery 1989)

WORKUP/STAGING

What are the typical presenting Sx of a pt with SFT or hemangiopericytoma?

Pts with SFTs present with a firm, painless, localized mass, typically in the extremities. HA or neurologic symptoms are typical in pts with CNS tumors (hemangiopericytomas).

How do hemangiopericytomas appear on imaging (CT, MRI)?

Hemangiopericytomas typically appear to be hypervascular lesions with diffuse contrast enhancement on CT or MRI.

TREATMENT/PROGNOSIS

What is the Tx paradigm for managing hemangiopericytoma?

Hemangiopericytoma Tx paradigm: Complete surgical resection is the mainstay of therapy + adj or neoadj RT, chemo, or CRT. Unresectable cases can be treated with either RT alone or CRT (inferior outcome).

Is there a role for chemo in the management of hemangiopericytoma?

Yes. Chemo may be used either preoperatively or adj. Antiangiogenic therapy is currently being explored, b/c these are highly vascularized tumors.

What is the typical PORT dose used for treating hemangiopericytoma after GTR?

The typical PORT dose is 50–60 Gy to the surgical bed with the margin varying by site; some studies (Ghia AJ et al., Neurosurgery 2013) suggest better LC with doses >60 Gy (HR 0.12, p = 0.045)

What is the 5-yr OS for hemangiopericytoma of the meninges?

5-yr OS is ~80% (Sonabend AM et al., J Neurosurg 2013)

What should be strongly considered adj for completely resected CNS hemangiopericytomas?

RT; in a recent SEER analysis of 227 pts (Sonabend AM et al., J Neurosurg 2013), GTR plus upfront adj RT was the only treatment that provided a significant survival advantage on multivariate analysis.

TOXICITY

What is an important consideration in following pts with a Dx of hemangiopericytoma?

High metastatic propensity despite aggressive initial treatment; as high as 68% at 15 yrs in some studies (Vuorinen VSP et al., Acta Neurochir 1996). Therefore, these pts require long-term follow-up care.

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