A 26-year-old female with history of migraine headaches presented with a 6-month history of intermittent 30 min episodes of left hemiparesthesia, typically preceded by kaleidoscopic vision changes. An MR image demonstrated a large infiltrative T2 hyperintense intrinsic tumor involving the right temporal and occipital lobes, herniating over the medial tentorial edge and causing mass effect on the brainstem (Fig. 1A, B). The tumor showed no evidence of abnormal enhancement or hyperperfusion. Given the size and complexity of a tumor involving the supratentorial and infratentorial fossae and multiple lobes, a staged resection was offered. An incision was fashioned to allow for both planned stages. A stage one right temporo-occipital craniotomy allowed resection of the posterior tumor using the lateral ventricle as a superior landmark, and a subtemporal transtentorial approach to resect tumor compressing the brainstem. Expectedly, the patient sustained post-operative incomplete left-sided homonymous hemianopsia. One month later, a stage two craniotomy resected the remaining anterior component resulting in gross total radiographic resection (Fig. 1C, D).

Magnetic resonance imaging over the course of treatment. Axial FLAIR (A) and coronal T1 post-contrast (B) images of tumor at time of presentation. Axial FLAIR (C) and T1 post-contrast (D) images following operative resection. Axial (E) and T1 post-contrast (F) images demonstrating subsequent formation of peripherally enhancing, hypodense extra-axial fluid collection with underlying mass effect and right to left midline shift. Axial (G) and coronal (H) T1 post-contrast images demonstrating multifocal recurrence including along the tentorium and convexity

Surgical resection was followed by standard protocol radiation and temozolomide, however three years later, the patient presented with worsening headaches and new subtle left lower extremity weakness. MR imaging now demonstrated atypical dural enhancement and what seemed to be a benign underlying right convexity subdural hematoma (Fig. 1E, F). Given her mild symptoms, evacuation was deferred in favor of right middle meningeal artery embolization resulting in temporary symptomatic relief and radiographic improvement in the hematoma size. However, 8 months following embolization, the patient was found to have focal areas of progressive diffuse dural thickening and enhancement along the convexity dura and tentorium (Fig. 1G, H), concerning for tumor recurrence. She underwent repeat craniotomy for resection and biopsy followed by re-irradiation of all enhancing areas over the dura and tentorium and chemotherapy (cyclic lomustine).

The patient discontinued Lomustine six months after the last resection and started Vorasidenib nine months following the last resection. At that time (9 months), the patient showed MR findings suspicious for progression. At ten months, there was clear progression on MR exam with peripheral nodular enhancement of the resection cavity and along the right subdural space with subdural thickening and extension.

Initial diagnosis demonstrated a mitotically active infiltrating glioma with nuclear pleomorphism but without sarcomatous morphology (Fig. 2A). Up to 5 mitoses were identified in 10 high-powered fields. GFAP IHC was diffusely positive. ATRX IHC was lost in tumor cells. IHC for p53 did not show aberrant over-expression. IDH1-R132H mutant-specific IHC was negative. Solid tumor NGS panel (Illumina NexSeq 550) on genomic DNA extracted from FFPE tissue showed an IDH1 exon 4 c.394C > T (R132C) point mutation. TEMPUS NGS confirmed the IDH1 mutation and showed ATRX and ARID1B frame-shift loss of function mutations. Characteristic oligodendroglioma mutations were not present (TERT, FUBP1, CIC). A MSH6 missense mutation c.2407G > C (p.D803H) of uncertain significance (VUS) was also identified via TEMPUS and the tumor was found to be microsatellite stable by IHC proxy with retained expression of MSH6. Germline testing for Lynch syndrome was not performed. The final diagnosis was anaplastic astrocytoma, IDH-mutant, CNS WHO grade 3 based on diagnostic criteria at the time.

Histology of initial resection and tumor recurrence. Hematoxylin and eosin-stained sections of A the initial resection demonstrating an infiltrative astrocytic neoplasm with irregular nuclear morphology and mitotic activity and B–C the re-resection specimen showing sarcomatous morphology. Stains on the re-resection specimen demonstrates D ATRX loss in the tumor and with retained expression in surrounding parenchyma, E reticulin fiber staining within the tumor, and F GFAP loss in the tumor with retained surrounding expression

Histology from the recurrent dural-based resection was overwhelmingly sarcomatous (>95% of overall tumor) with tumor morphologically characterized by spindled cells containing atypical nuclei embedded in a myxoid and collagenous background (Fig. 2B, C). An adjacent focus of glial tumor component was also present. GFAP and OLIG2 were not expressed in the sarcomatous regions of the tumor but positive within the glial component. ATRX was lost in both the sarcomatous and glial components. p53 was not overexpressed. Sarcomatous regions of the tumor were reticulin fiber rich. There was extensive strong positivity for muscle-specific actin in the sarcomatous regions. A combined GFAP/Ki67 stain showed rare, atypical GFAP-positive proliferating tumor cells in the glial component. The full IHC profile is included in Table 1. NGS was performed on the sarcomatous component, which contained the same IDH1-R132C point mutation as the initial resection specimen.

Genomic DNA was extracted, and chromosomal microarray studies were performed to evaluate the clonal progression of the tumor molecular features on the following two specimens: (1) the original tumor and (2) the sarcomatous component of the glial tumor. Genome-wide DNA Methylation was performed on the following three specimens: (1) the original tumor and (2) the sarcomatous component of the glial tumor; and (3) the glial component of the recurrent tumor.

CMA studies were performed on the OncoScan CNV Plus microarray assay from ThermoFisher Scientific and the results were interpreted using the ChAS software. Copy-number alterations greater than 50–100 kb in cancer genes or greater than 3 MB outside clinical oncology significant regions, and CnLOH greater than 10 MB were reported. Genome-wide DNA Methylation Array Studies were performed on the Infinium EPIC-8 v2.0 HD Methylation Beadchip. Interpretation of the genomic DNA methylation results were completed on v12.8 of the DKFZ/Heidelberg classifier [11].

CMA results from the initial resection showed loss of chromosome 9, including the CDKN2A/B locus, chromosome 17p CnLOH (Fig. 3A), 17q gain, and loss of chromosome X. There was neither co-deletion of chromosomes 1p/19q nor was there CnLOH in those chromosome arms (Fig. 3A). The sarcomatous component of the recurrence demonstrated a complex karyotype with abnormalities involving every chromosome, but notable for the same 17p CnLOH (Fig. 3B, C), which supports the clonal relationship between the sampled initial resection and sampled recurrence. In addition, the sarcomatous component did not show 1p/19q co-deletion, although there was LOH of 1p and gain of 19q. Loss of heterozygosity was seen at the IDH1 gene locus; however, there is no definite evidence to support gross copy number alterations at this locus (Supplement 1).

Chromosomal Microarray of initial and recurrent tumor. Copy number plots from chromosome 1p (left) to Y (right) for the initial resection (A) and recurrence (B). The initial resection (A) shows loss of chromosome 9/CDKN2A/B (red arrow) and LOH at chromosome 17q, including the TP53 locus (blue arrow). No 1p/19q co-deletion was observed. Recurrent tumor (B) showed a complex karyotype with retained 17q LOH breakpoint but no co-deletion nor LOH at 1p/19q. Expanded chromosome 17 plots (C), which correspond with blue and pink boxes in A and B, showed loss of heterozygosity with the same breakpoint (green arrow) in both initial sample (blue) and recurrent sarcomatous tumor (pink)

DNA Methylation results showed the initial resection matched with high confidence to methylation class astrocytoma, IDH-mutant, low-grade (0.89) with the minor subset class oligodendroglioma, IDH-mutant, 1p/19q co-deleted (0.11). Methylation profiling of the glial component of the recurrence matched with high confidence to methylation class astrocytoma, IDH-mutant, low-grade (0.99); however, the sarcoma matched with high confidence to the MC oligosarcoma, IDH-mutant, with a final confidence score of 0.90. The full methylation classifications for the separate resection specimens and different histologic morphologies are detailed in Table 2.