Imaging features of extraaxial
Magnetic resonance imaging (MRI) of his brain was obtained and revealed an extraaxial
mass in the inferior fourth ventricle extending through the foramen magnum and impressing upon the pontomedullary junction and medulla with posterior compression of the cerebellar tonsils.
Intraaxial lesions enhance when blood-brain barrier breaks down, and extraaxial
lesions usually enhance due to high vascularity (8).
4 The specificity of this marker has been documented in only a handful of studies, comprising both intraaxial and extraaxial chordomas.
8) Recently, extraaxial chordomas have also been documented.
Meningiomas, which constitute 15% of primary brain tumors in adults, are extraaxial
, slow-growing, and histologically mostly benign.
7) Hydrocephalus, lacrimal mass, extraaxial
mass, enlarged pituitary stalk, and enhancing clumped nerve roots are other findings.
Intraventricular meningiomas (Figure 28) calcify in approximately 50% of cases, (62) with calcification patterns similar to the extraaxial
13) The hematogenous route is likely and additional intra-axial or extraaxial
lesions may be a diagnostic clue.
Seven months later, he was admitted to the hospital with seizures, at which time extraaxial
central nervous system (CNS) metastases were found (Figure 1).