Choroid Plexus Carcinoma and Papilloma
BACKGROUND
What % of intracranial neoplasms do choroid plexus (CP) tumors represent in adults and children?
In adults, CP tumors account for <1% of primary intracranial neoplasms, whereas CP tumors represent up to 5% of pediatric brain tumors.
What are the most common locations of CP tumors in children vs. adults?
Children: Lat ventricles
Adults: 4th ventricle
What is the name for the benign CP variant, and how frequent is it? How about the malignant variant?
Benign variant: choroid plexus papilloma (CPP)/WHO grade I (60%–80% of cases)
Malignant variant: choroid plexus carcinoma (CPC)/WHO grade III (20%–40% of cases)
What are the pathologic features of WHO grade I papillomas vs. WHO grade II atypical papillomas vs. WHO grade III carcinomas?
WHO grade I CPP are characterized by papillary formation and lack of mitosis. WHO grade II atypical papillomas resemble WHO grade I papillomas but have increased mitoses. WHO grade III CPC are characterized by nuclear atypia, pleomorphism, frequent mitoses, and invasion of brain parenchyma. (Louis D et al., Acta Neuropathol 2007)
With what syndrome is CPC associated?
Li-Fraumeni, due to p53 mutation (Tabori U et al., JCO 2010)
What proportion of children present with metastatic Dz at Dx?
One-third of children present with metastatic Dz, all typically with CPC.
What is the most common age of presentation for these tumors?
70% of pts are <2 yo.
What % of CPCs can have CSF seeding? How about CPPs?
Up to 40% of CPCs have CSF seeding, but such seeding is very rare for papillomas.
What are the 2 most important prognostic/predictive factors for CP tumors?
Histologic grade and extent of resection
How does age affect prognosis?
Patients >40 yrs have poorer prognosis, followed by children <10 yrs. Those in the 10–40 yo group fare the best. Sex is not a prognostic factor.
WORKUP/STAGING
What are the 2 most common Sx at presentation in pts with CP tumors?
Hydrocephalus and HA (due to CSF overproduction and flow obstruction)
What studies need to be performed during the workup for CP tumors?
MRI of brain and spine and CSF cytology
What is the differential for an intraventricular mass?
Ependymoma, subependymoma, central neurocytoma, subependymal giant cell astrocytoma, CPP, CPC, meningioma, metastasis (Koeller KK et al., Radiographics 2002)
What are the radiologic features of CPPs vs. CPCs?
CPP: lobulated, solid, well-demarcated intraventricular mass that is isodense to mildly hyperdense on CT. On MRI, homogenous with intense contrast enhancement. CPC: usually larger than papillomas with heterogeneous signal patterns on CT and MRI; may contain calcifications, necrosis, and hemorrhage and frequently invade brain parenchyma.
TREATMENT/PROGNOSIS
What is the general Tx paradigm for CP tumors?
CP tumor Tx paradigm: max safe resection (after embolization/chemo, if necessary) +/– chemo (younger pts) and/or RT (if age >3 yrs)
What are the indications for RT in pts with CP tumors?
Age >3 yrs and 1 of the following: carcinoma histology, +CSF/spine Dz (CSI), or recurrent tumors
What is the role of RT in CPPs after STR?
No RT is necessary upfront, as only 50% of STR pts require reoperation, surgical salvage is good, and reoperation may not be needed until yrs later. Consider RT if there is a STR after recurrence. (Mayo data: Krishnan S et al., J Neurooncol 2004)
What is the recommended EB dose for CPPs?
Conventional RT: >50 Gy to localized field
Stereotactic RT: 12 Gy to 50% IDL (Pittsburgh data: Kim IY et al., J Neurosurg 2008)
What is the strongest indication for CSI?
Positive neuroaxis staging. If pt >3 yo, CSI can be given to 36 Gy followed by boost to primary site and/or mets.
What makes the resection of CPCs especially challenging?
CPCs are very friable and extremely vascular.
What can be attempted preoperatively to make resection easier?
Embolization (reduces intraoperative bleeding risk) or neoadj chemo
What agents may be used neoadjuvantly (after Bx and before 2nd-look surgery) for CPCs?
Ifosfamide, carboplatin, and etoposide (Toronto data: Wrede B et al., Anticancer Res 2005)
What data support the use of adj chemo and/or RT in CPCs?
Johns Hopkins Hospital data: 75 pts. GTR was better than STR (84% survival if GTR vs. 18% if STR). Adj RT offered a survival advantage after STR ( p = 0.004) but not after GTR. (Fitzpatrick LK et al., J Neurooncol 2002)
What study supports delaying RT in very young children with CPCs?
“Baby” Pediatric Oncology Group study: 8 CPC pts treated with surgery, chemo, and delayed RT without any adverse sequelae (Duffner PK et al., Pediatr Neurosurg 1995)
What data support CSI over smaller RT fields in CPC?
Mazloom A et al. reviewed the literature and found 56 pts with CPC; 5-yr PFS with CSI was 44.2% vs. 15.3% with smaller fields (IJROBP 2010)
What do the data show with regard to RT after GTR for CPC?
Canadian data (Wolff JE et al., Lancet 1999): 5-yr OS was 70% with RT and 20% without RT.
What is the 5-yr survival rate for CPPs?
The 5-yr survival rate is 80%–100% following gross total resection and 68% following subtotal resection.
What is the 5-year survival rate for CPCs?
CPCs are significantly more aggressive, with greater tendency for leptomeningeal dissemination and/or recurrence. The 5-yr OS is only 20%–30%.
TOXICITY
What are some prominent side effects from RT in the pediatric population with CP tumors?
Skull hypoplasia and neurocognitive/endocrine deficits
In patients with Li-Fraumeni syndrome, what long-term risk is of special concern after RT?
Radiation-induced 2nd malignancies
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