1 Cerebellar Juvenile Pilocytic Astrocytoma

CASE 1

Clinical Presentation

A child presents with vomiting, headaches, and, later, personality changes.

Figure 1A

Figure 1B

Figure 1C

Figure 1D

Figure 1E

Figure 1F

Radiologic Findings

Initial CT without contrast demonstrated dilated third ventricle and temporal horns (with compressed hippocampi) (Fig. 1A). A large, rounded hypodense mass is noted behind the fourth ventricle, in the vermis and adjacent portions of the cerebellar hemispheres. This mass appears cystic with two solid mural nodules, one anterior on the left and the other posterior on the right with calcification. Nonenhanced MR images show similar findings with low T1 (Fig. 1B) and high T2/FLAIR (Figs. 1C and 1D). The cyst content presents attenuation and signals different from the adjacent CSF. Following contrast, MRI (Figs. 1E and 1F) demonstrates enhancement of the cyst wall and of the solid mural nodules. Note the anterior third ventricle bulging into a large cisternal space (presurgical ventriculocisternotomy possible to alleviate hydrocephalus) and the tonsillar herniation through the foramen magnum (risk of acute compression of the medulla).

Vomiting first led to abdominal investigations before the increase in intracranial pressure was evident.