Evaluation of Supratentorial Pleomorphic Xanthoastrocytomas in Children

Examination

• No focal neurological signs: Usually children with PXAs have no focal neurological signs.

Laboratory Tests

• Standard: Standard preoperative blood tests should be performed, but no abnormalities are expected.
• Type and crossmatch: It is necessary to type and crossmatch packed red blood cells in preparation for inevitable bleeding at surgery in young children.

Radiologic Tests

Regular x-rays and ultrasound

CT scans

• Initial assessment: A CT scan is often done as the first assessment in the emergency room, especially when MRI is unavailable.
• Hypo- or isodense cystic tumor: A large cyst is usually seen in PXA. The solid portions of the tumor are hypo- to isodense and in contact with the pia.
• Contrast: The solid portion of the tumor has a uniform enhancement.

MRI

• T1-weighted MRI: The tumor is isointense to hypointense, with 70% of PXAs having leptomeningeal involvement.
• T2-weighted MRI: The tumor is isointense to hypointense with little surrounding edema.
• Contrast enhancement: The tumor enhances vividly with gadolinium. Some tumors have a dural tail.
• Cysts: Cysts are present in 50–60% of cases and will have CSF intensity, sometimes slightly more intense on T2-weighted images than CSF.

Nuclear Medicine Tests

• PET: FDG-PET studies show hypermetabolism in PXAs, whether or not they are anaplastic or grade II (26, 27).

Electrodiagnostic Tests

• Seizure evaluation: EEG can confirm the onset of the seizures to the location of the tumor and might show interictal spikes.

Neuropsychological Tests

• Language evaluation: Patients with large temporal tumors in the dominant hemisphere might show subtle language deficits.

Correlation of Tests

• Appearance on imaging: The location of the tumor on the CT/MRI scans and EEG findings can be used to determine the best surgical approach as well as the extent of resection.