Epithelioid glioblastoma

Case contributed by James Q Le

Presentation

Memory loss and anomic aphasia for 1 month.

Patient Data

Age: 17 years
Gender: Female
mri

There is a cortically based mass in the superior aspect of the posterior left temporal lobe with solid and cystic components. There is significant vasogenic edema surrounding the lesion. The lesion measures approximately 1.9 x 1.9 x 1.9 cm.

Post-resection

mri

There has been interval resection of the left posterior temporal mass, with no distinct residual tumor evident. There is subtle peripheral restricted diffusion at the margins of the resection cavity, and prominent susceptibility hypointense signal within and surrounding the surgical bed, all expected postsurgical changes. Surrounding vasogenic edema is not significantly changed from the preoperative study.

Histology

Microscopic description: The sections show a pleomorphic cellular glial neoplasm. There are increased mitotic figures (at least 13 mitotic figures per 10 high power fields). Rare eosinophilic granular bodies are identified. There are areas of necrosis with pseudo-palisading in addition to vascular proliferation.

This high-grade astrocytoma resulted positive for TERT promoter mutation and was found to harbor concurrent chromosomal gain of 7 and loss of 10, with homozygous loss of CDKN2A/B. This molecular profile is consistent with IDH-wildtype glioblastoma. When considered in conjunction with this tumor's epithelioid morphology and BRAF V600E mutation, the overall findings are most consistent with epithelioid glioblastoma, IDH-wildtype (CNS WHO grade 4).

Macroscopic description: Left temporal tumor. Received fresh for intraoperative consultation is a 1.4 x 1.1 x 0.4 cm aggregate of tan and red tissue. 

Final diagnosis: Epithelioid glioblastoma, IDH-wildtype (CNS WHO grade 4)

Case Discussion

Epithelioid glioblastomas (eGBMs) are among the rarest variants of glioblastoma with an overrepresentation of BRAF V600E mutations in 50% or more cases.1 

There are three diagnostic subsets based on molecular analysis 1:

  1. PXA-like most commonly in children and young adults
  2. IDH-wild type GBM-like most commonly in older adults, and
  3. RTK1 GBM-like most commonly in children and young adults

Pediatric epithelioid glioblastomas may present with acute hemorrhage. Leptomeningeal dissemination and metastases outside the CNS are possible.2 

As with most glioblastomas, eGBMs are best followed with MRI. Radiographic features found in the majority of tumors include diffusion restriction of the solid tumor component and perilesional vasogenic edema. Central necrosis may also be present, with the degree of necrosis being a negative prognostic factor. Mass effect may also be present depending on the size of the tumor and the extent of edema. These tumors are most frequently located in the cerebrum and diencephalon.3

This patient presented as an adolescent with a 1-month history of memory loss and aphasia. She subsequently had a resection with adjuvant chemotherapy and radiation treatment. 

Case authors: Le J, Senti M, Moore A

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