6-year-old female with history of GBM status post radiation therapy. Redemonstrated is a large focus of T2 hyperintensity in the posterior pons and extending superiorly into the right cerebral peduncle and inferiorly bulging into dorsal aspect of the upper medulla. Although the transverse aspect has slightly decreased, there is a new focus of T2 hyperintense extension involving previously uninvolved anterior right paramedian pons. As before, there is irregular peripheral enhancement with a large central focus of non-enhancement, associated with susceptibility abnormality. Overall, the peripheral enhancement appears thicker, and more nodular, and there is new enhancement extending into the aforementioned new T2 hyperintense abnormality as well as new enhancement extending into the left cerebral peduncle. As before, there is mass effect with flattening and posterior displacement of the fourth ventricle and mild supratentorial ventricular enlargement which is stable. The cortical sulci remain within normal for stated age and midline is maintained. There is no additional foci of parenchymal signal abnormality or parenchymal/leptomeningeal abnormal enhancement. Expected vascular flow voids are demonstrated. New fluid is present within a few dependent left mastoid air cells, and mild inflammatory change in the right mastoid air cells appear stable.
Redemonstrated is a necrotic pontine mass with a thick irregular rim of enhancement and surrounding edema. Overall, the peripheral enhancement appears thicker, and more nodular, and there is new enhancement extending into a region of new T2 hyperintense abnormality, as well as new enhancement extending into the left cerebral peduncle. The differential diagnosis would include tumor progression versus radiation necrosis.