Presentation
Car accident. Single driver. Previously well. Abnormal CT brain (not shown). For further assessment.
Patient Data
On the left two closely related, predominately cystic lesions are identified with abundant surrounding vasogenic edema within the left frontal lobe. These lesions have susceptibility-induced signal loss compatible with blood product and seemed to be based upon the adjacent dura which demonstrates
more extensive thickening. No invasion of the adjacent skull. The fluid within the cystic components demonstrates very facilitated diffusion.
Cerebral blood volume is increased within the solid components and reduced within the area of edema. MR spectroscopy of the peripheral component is uninterpretable due to its location adjacent to bone, but demonstrates a normal trace in the edematous white matter.
The remainder of the brain is normal.
Conclusion:
Unusual supratentorial dural-based lesion(s). The differential includes hemorrhagic metastases (is there a history of melanoma or another primary?) or a primary brain
tumor (e.g. glioblastoma or pleomorphic xanthoastrocytoma). The appearances are not those of a pyogenic abscess, but unusual infective agents cannot be categorically excluded, although I feel this is most unlikely.
Case Discussion
The patient went on to have a resection.
Histology
Sections show fragments of a highly cellular tumor. The tumor cells form diffuse sheets. They have enlarged, pleomorphic nuclei, vesicular chromatin, and are set in a fibrillary background. Mitotic figures are identified. There is microvascular proliferation and palisading necrosis.
Immunohistochemistry
GFAP: positive
OLIG2: positive
IDH1 R132H: negative (not mutated)
ATRX: positive (not mutated)
p53: wildtype pattern
p16 CDKN2A: negative (lost)
Ki67: up to 50%
Final diagnosis
Glioblastoma, IDH-wildtype (CNS WHO grade 4).
Discussion
This is an unusual tumor but elegantly shows how not all lesions that involve the dura have a dural origin. It is worth remembering that superficial lesions can pass through the pia matter and adhere to the the dura with reactive dural thickening or direct involvement.
Note also, that as the patient is over 55 years of age and has a negative IDH-1 R132H immunohistochemistry, the chances of having another IDH mutation is remote and therefore sequencing need not be performed to designate this tumor as a glioblastoma. If the patient was younger, then sequencing would be required.
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