Reason: 6 year old with juvenile pilocytic astrocytoma receiving vinblastine - any signs of progression? History: JPA. Postsurgical findings in the right posterior fossa appear similar to the prior exams. There is redemonstration of a predominantly extra-axial soft tissue mass at the right cerebellopontine angle measuring approximately 3.4 x 1.9 cm (801/20), previously 3.4 x 1.7 cm. The tumor is stable in extent, encasing the basilar and vertebral vertebral arteries, extending into Meckel's cave and the right internal auditory canal, and tracking along the posterior lateral aspect of the spinal cord beyond the inferior slice of the MRI. Cystic components more inferiorly are unchanged in size. There is decreased FLAIR signal intensity with overall increased heterogeneous appearance on this sequence, likely reflecting treatment-related changes. Postcontrast images show no significant enhancement within the lesion. There is persistent significant mass effect on the leftward displaced lower brainstem and upper cervical cord, with slight increased visualization of the foramen of Magendie compared to remote comparisons.There is no evidence of intracranial hemorrhage or acute infarct. The ventricles and basal cisterns are stable in size and configuration. A right parietal ventriculostomy catheter is unchanged in position with its tip in the midline. There is no midline shift or herniation. The major cerebral flow voids are intact. There has been resolution of severe mucosal thickening of the maxillary sinuses.
No significant interval change in size of a predominantly extra-axial posterior fossa juvenile pilocytic astrocytoma, although with interval increased heterogeneity on FLAIR with overall decreased FLAIR hyperintensity, which likely reflect posttreatment changes.