11 year old female with a sub-acute history of headache, nausea and visual disturbance. CT and MR of the brain was performed.
This patient presented with a three day history of pain behind the left ear, a two day history of headache associated with nausea and one day history of visual disturbance. On examination the patient was found to have a left sided temporal hemianopia.
A head CT was performed; this revealed a large, predominantly cystic lesion in the right frontal lobe with abnormality and expansion of the right sphenoid bone. The inferior portion of the lesion enhanced following IV contrast. (Fig 1 & 2)
Subsequently an MRI scan was performed. This showed a large cystic abnormality in the right frontal lobe with at least two separate cystic components. The areas of enhancement were demonstrated extra-axially after administration of gadolinium. These enhancing areas were also seen to have small, intratumoural, cystic components in them. The larger, extratumoural cystic components did not exhibit enhancement. (Fig. 3, 4 & 5)
Meningeal tumours are less common in children than adults. Only 2.5% of all primary paediatric CNS tumours in the USA from 1995-1999 were meningeal in origin. For all age groups combined they comprise 22%.
In children unlike the adult population, meningiomas are more likely to be associated with neurofibromatosis type 2 and prior irradiation.
In the paediatric age group, meningioma appearances can often be atypical including large size, cyst formation, intraparenchymal origin and a greater tendency towards malignancy.
Cystic meningiomas comprise 2-4% of all meningiomas. In children they account for around 10% and of these 55-65% occurs in the first year of life.
Cystic meningiomas can be defined by the location of the cystic component. There are intratumoural cysts, extratumoural (peritumoural) cysts and mixed.
These differences in cyst location are thought to derive from different pathological processes. Intratumoural cysts are most likely the endpoint of microcystic degeneration, necrosis or haemorrhage. Peritumoural cysts may represent the endpoint of a reactive gliosis, intense peritumoural oedema or may be due to widening of the CSF space or trapping of CSF in the spaces compressed by the tumour.
MR imaging with contrast can reliably distinguish between intratumoural and peritumoural cysts. Intratumoural cysts show cyst wall enhancement (containing tumour cells) and peritumoural show no wall enhancement (cyst wall containing gliotic tissue). These considerations are important from a surgical viewpoint as they have implications for future surgical management. If there is cyst wall enhancement, the cyst and cyst wall will need to be removed at surgery.
Imaging findings in these tumours can be confusing because of the cystic component, meaning they could be confused with glial tumours. The dural tail sign is not reliable in the paediatric age group. In addition meningiomas in the paediatric age group can be intraparenchymal in origin.
In this case CT and MRI were complimentary. The CT showing the abnormality of the right sphenoid bone. MRI showed the enhancing extra axial tumour and the connection to the cystic component. A differential diagnosis of cystic meningioma could be made in this circumstance from the imaging findings alone.
Differential Diagnosis List