Hemangiopericytoma and solitary fibrous tumors Flashcards
How are hemangiopericytomas (HPCs) classified vs. solitary fibrous tumors (SFTs)?
The revised 2013 (4th edition) WHO classification schemata now groups these tumors together as SFTs. Current neuropathologic practice, however, still distinguishes b/t HPC and SFT.
Are SFTs benign or malignant lesions?
Although most cases are benign, SFTs may display metastatic potential in 20% of cases. In general, meningeal HPCs behave more aggressively than
SFTs of other sites.
What is the cell of origin of SFTs?
HPCs were originally thought to be a vascular neoplasm originating from pericytes of the smooth muscle cells of vessels. Currently SFTs are recognized as a form of fibroblastic/myofibroblastic tumors
What fusion protein is noted in HPCs/SFTs?
NAB2–STAT6 fusion protein, arising from recurrent intrachromosomal rearrangements on chromosome 12q. (Schweizer, Acta Neuropathol 2013)
What is the rate of LR for resected CNS HPC?
Very high, the recurrence rate is as high as 92% at 15 yrs in modern series. (Schiariti et al., Journal of Neurosurgery 2011)
What does the prognosis of SFTs primarily depend on?
The prognosis depends primarily on tumor location and ability to achieve GTR; for example, for CNS tumors, supratentorial tumors have a better prognosis than PF and base of skull tumors.
What are the typical presenting Sx of a pt with SFT or HPC?
In the CNS, HA or neurologic Sx are typical in pts with HPC. At other sites pts with SFTs present with a firm, painless, localized mass.
How do intracranial/HPCs appear on imaging (CT, MRI)? What do they have in common with meningiomas?
On CT HPCs are typically solid, discrete, extra-axial masses. They hyperattenuate with marked heterogeneous enhancement after contrast. On
T1 MRI the lesions are isointense and heterogeneous with areas of both low and high-signal intensity and prominent vascular flow voids. The hypervascularity shows marked heterogeneous enhancement after gadolinium. Tumors show thickening of the adjacent meninges (dural tail) or tentorium. Erosion of the adjacent skull may also occur. (Keraliya et al., Radiol Clin N Am 2016)
What is the Tx paradigm for managing SFT/HPCs?
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.
Is there a role for systemic therapy in the management of SFT/HPCs?
Yes. Sunitinib is the effective therapy in pts with advanced SFT/HPC. (George S et al., JCO 2009; Stacchiotti S, Ann Oncol 2012) Sorafenib
therapy is another multitargeted TKI that has some activity in SFT. (Valentin et al., Invest New Drugs 2013) Bevacizumab and TMZ were shown to have evidence of activity. (Park et al., Cancer 2011)
What is the typical PORT dose used for treating SFT/HPCs 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). SRS (12–20 Gy) may also
be used.
What is the 5-yr OS for HPC of the meninges?
5-yr OS is 83%. (Sonabend AM et al., J Neurosurg 2014)
What should be strongly considered adj for completely resected HPC?
RT. In a recent SEER analysis of 227 pts (Sonabend AM et al., J Neurosurg 2013), GTR plus adj RT was associated with improved OS.
What is the metastatic propensity of HPCs?
High metastatic propensity despite aggressive initial Tx; as high as 68% at 15 yrs in some studies. (Vuorinen VSP et al., Acta Neurochir 1996) Therefore, these pts require long-term f/u care.
