Posterior fossa tumor epidemiology
In adults, the most common expansile “mass” lesion in the posterior fossa is a subacute stroke, whereas the most common neoplastic lesion in the posterior fossa is cerebellar metastasis (intra-axial) or vestibular schwannoma (extra-axial) 1)
Although it is true that posterior fossa tumors are much more common in children than in adults the distribution does vary with age:
0 to 3 years of age: supratentorial > infratentorial
4 to 10 years of age: infratentorial > supratentorial
10 to early adult hood: infratentorial = supratentorial
adults: supratentorial > infratentorial
Overall 50-55% of all brain tumors in children are found in the posterior fossa.
Posterior fossa hemangioblastomas are the most common primary intra-axial posterior fossa tumor in adults). May occur in the cerebellar hemisphere, vermis, or brainstem.
In a a series of 30 patients, metastasis was the most common posterior fossa lesion (20%), followed by vestibular schwannomas (17%) and arachnoid cysts (13%), meningiomas, medulloblastoma, and pilocytic astrocytoma (10% each) and epidermoid, ependymoma, and hemangioblastoma (7% each). The mean ADC value of benign tumors was higher than that of malignant tumors, and this difference was found to be significant (p = 0.012). The cut-off ADC value 1.21x 10-3mm2/s had a sensitivity of 81.82% and specificity of 80.47%. MRS metabolites played an additional role in differentiating benign from malignant tumors. Conclusion A combination of conventional MRI, DWI, ADC values, and MRS metabolites showed good diagnostic accuracy to differentiate between the various posterior fossa neoplastic tumors both in adults and children 2).