Presentation
Headache, attacks of vomiting and disorientation.
Patient Data
A large enhancing partially-cystic mass is centered at the left frontotemporal lobe and measures 54 x 64 x 73 mm. The nodular mildly hyperdense portions show strong contrast uptake in an area measuring 25 x 18 mm, extending into the left frontal lobe. The lesion exerts mass effect in form of rightward subfalcine herniation and left uncal herniation. There is associated rightward midline shift (displacing the midline by 12 mm), with asymmetric dilatation of the lateral ventricles and findings of transependymal CSF permeation.
After the tomographic report and surgical resection, histopathologic evaluation was performed. The results were: WHO grade II, 10 mitotic figures/10 HPF, brain invasion, increased cellularity, small cells with high nuclear-to-cytoplasmic ratio, large prominent nucleoli and foci of spontaneous necrosis.
Images of the same patient, processed with the program AutoboneXpress, where we observe the meningeal dependence, especially in the second image.
Case Discussion
Meningiomas constitute the most frequent primary intracranial tumor (15-20%) and the most frequent extraparenchymal tumor in the supratentorial compartment in adults. In the posterior fossa, it is the second most common extraparenchymal tumor after schwannoma 3. It is an extra-axial and intradural lesion with characteristic image characteristics.
This lesion is not typical of meningioma, specifically due to the characteristics of the extensive cystic change and the possible invasion of the cerebral parenchyma. The differential diagnosis includes atypical/malignant meningioma, dural metastasis, lymphoma and sarcoma (osteosarcoma, Ewing, gliosarcoma, etc.). According to the images, the initial diagnosis was glioblastoma. However, in retrospect, there was only mild vasogenic edema (less than what can be expected with glioblastoma) and the presence of dural tail was noted (highlighted by the Autobone Express program), a characteristic present in 80% of meningiomas but not specific for meningioma. Based on surgical histopathology, the final diagnosis is an atypical meningioma.
Thanks to the Radiologist Rosa Aguirre.