====== 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)
((Shih RY, Smirniotopoulos JG. Posterior Fossa Tumors in Adult Patients. Neuroimaging Clin N Am. 2016 Nov;26(4):493-510. doi: 10.1016/j.nic.2016.06.003. Epub 2016 Sep 2. PMID: 27712791.))
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Although it is true that [[posterior fossa tumor]]s are much more common in [[child]]ren than in [[adult]]s 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 tumor]]s in children are found in the [[posterior fossa]].
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[[Posterior fossa hemangioblastoma]]s are the most common primary intra-axial [[posterior fossa tumor]] in adults). May occur in the [[cerebellar hemisphere]], [[vermis]], or [[brainstem]]. 
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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
((Bose A, Prasad U, Kumar A, Kumari M, Suman SK, Sinha DK. Characterizing Various Posterior Fossa Tumors in Children and Adults With Diffusion-Weighted Imaging and Spectroscopy. Cureus. 2023 May 17;15(5):e39144. doi: 10.7759/cureus.39144. PMID: 37378152; PMCID: PMC10292159.)).