Evaluation of Supratentorial Central Neurocytomas in Children

Examination

• Nonspecific: The clinical examination is generally not very informative. Clinical features of raised ICP may be the first manifestation, and these patients may present with early papilledema due to the development of hydrocephalus.

Laboratory Tests

• Nonspecific: No specific laboratory test is indicated . In the rare instance of a neurocytoma being located near the hypothalamus, endocrine evaluation may be needed.

Radiologic Tests

• Hydrocephalus common finding: Both CT and MR scans may show hydrocephalus.

CT Scan

• Isodense to slightly hyperdense with enhancement: On CT scan the mass is usually located in the lateral ventricle, generally in the anterior body and frontal horn. The mass is usually isodense or slightly hyperdense. Enhancement is observed after contrast administration, although the enhancement may be variable.
• Calcifications and cystic changes: These changes have been observed.
• Differential diagnosis: Differential diagnosis includes subependymal giant cell astrocytomas and subependymomas.

Axial CT scan of a neurocytoma: Note the location anteriorly in the lateral ventricles, with both cystic changes and calcification

MRI

• Iso- to hyperintense on T1- and T2-weighted imaging: the tumor shows normal to high signal intensity and exhibits moderate to strong enhancement after gadolinium injection.

T1-weighted axial MRI with gadolinium enhancement of Central neurocytoma: Note the strong enhancement with gadolinium and the generally rounded and smooth margins of the tumor

T2-weighted axial MRI of a Central Neurocytoma: Shown is a well-circumscribed hypointense lesion

T1-weighted coronal MRI with gadolinium enhancement of a Central neurocytoma: Note the well-circumscribed nature of the tumor projecting inward from the ventricular wall

•  Well circumscribed on proton-gradient images: Proton-gradient images reveal a well-circumscribed lesion that projects inward from the lateral ventricular wall.
• Spectroscopy: In one study (23), volume-selective single-voxel proton magnetic resonance spectroscopy was performed with a 1.5-T unit using a point-resolved spectroscopy sequence (TR/TE = 2000 ms/135 and 270 ms) to obtain spectra of a single 8-cc voxel. The ratios of Cho to creatine/phosphocreatine and Cho to N-acetylaspartate were significantly higher than ratios in normal brain. A lactate signal was present, and an unidentified signal was also observed at 3.55 ppm, which might have been produced by inositol or glycine.

Angiography

• Homogeneous blush: Cerebral angiography shows homogeneous vascular staining with a blush persisting into the late venous phase.

Nuclear Medicine Tests

• Increased FDG uptake: Central neurocytoma is a benign neuronal tumor with a favorable prognosis. It is typically characterized by decreased uptake of18F-fluorodeoxy glucose (FDG), and any increased uptake of FDG in patients suffering from this tumor would be highly unusual. A case of central neurocytoma with intense FDG uptake would raise the suspicion of atypical neurocytoma (24).

Correlation of Tests

• MRI appearance characteristic: The classical appearance on MRI of a central neurocytoma in young patients should preclude the need for most other studies.