We received an unusual case on our neuropathology service this week. The specimen was a 4 cm frontal, extra-axial mass that was dural-based, abutting the falx cerebri. MRI showed intense enhancement with surrounding vasogenic edema and a small dural tail. There was only mild mass effect and diffusion weighted imaging (DWI) showed no diffusion restriction. Cerebral arteriography showed a hypervascular lesion. Left middle meningeal artery embolization was performed preoperatively. At craniotomy the tumor was liquid and necrotic-appearing and the excised specimen was sent to us for pathological examination. The histological appearance is depicted below (click on photos to get higher resolution):
Glassy, eosinophilic cytoplasm with inclusions
Atypical cytology with some prominent nucleoli (occasional mitoses were also identified [~1-2 per 10 high-powered fields])
Focal areas of necrosis and hemorrhage
MIB-1 (Ki-67) immunostain showing a 15-20% proliferation rate.
Additionally, a vimentin immunostain showed strong diffuse cytoplasmic positivity and an EMA immunostain showed positive membrane staining. Cytokeratin immunostain was negative. How would you diagnose this case?
Glassy, eosinophilic cytoplasm with inclusions
Atypical cytology with some prominent nucleoli (occasional mitoses were also identified [~1-2 per 10 high-powered fields])
Focal areas of necrosis and hemorrhage
MIB-1 (Ki-67) immunostain showing a 15-20% proliferation rate.
