Atypical meningioma - intraosseous

Discussion:

The lesion was incidentally discovered but upon further history gathering, the lesion was symptomatic. Thus, the patient was planned for surgical resection. Preoperative lumbar puncture was performed given the imaging finding of empty sella; the open pressure was 10 cm of water, thereby excluding intracranial hypertension. The surgery consisted of right frontotemporoparietal craniectomy, cranioplasty, resection of intradural tumor, and duraplasty. Gross total resection was achieved.

Histopathology revealed that the lesion was an atypical meningioma, WHO grade II. Additional notes from the pathology report: The tumor shows areas of high cell density, focal necrosis, prominent nucleoli, and foci of patternless growth. The mitotic count is 3 per 10 high power fields. The Ki-67 proliferation index is 2.8%. The tumor diffusely involves bone, skeletal muscle, and dura.

On imaging, the fact that the lesion is centered in the bone is consistent with intraosseous meningioma, albeit this terminology is controversial when the lesion also extends outside the bone. Given the dural involvement, it may also be reasonable to call this an en plaque meningioma that subsequently extended into bone.

Given the histology, the patient underwent postoperative radiation to the resection cavity in an effort to minimize risk of neurologic morbidity from tumor recurrence.

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