Pseudoprogression in an IDH-mutant astrocytoma, grade 4

45-year-old female with a left frontal IDH-mutant astrocytoma, grade 4 (no homozygous deletion of CDKN2A) treated with combined radiation plus daily temozolomide followed by 6 monthly cycles of temozolomide. All images are axial T1-weighted postcontrast MRI showing postsurgical changes and a resection cavity in the left frontal lobe. The baseline scan (A) was obtained 7 months after completion of monthly temozolomide. 3 months later (B), there is a new small nodule of periventricular enhancement in the wall of the left lateral ventricle (arrows). On subsequent scans (C to E), there is a gradual increase and spreading of the enhancement around the left lateral ventricle, reaching a maximum in scan E, followed by spontaneous resolution (F to H). Some residual enhancement remains at the last timepoint (H).