A Posterior Fossa Epidermoid Cyst without Restriction by DWI, A Rare Finding

Objective: To present the typical, and in this case, atypical MRI DWI findings of a posterior fossa epidermoid cyst. Design/Patient/Material: A single case of a 27 year old female with a one year history of intermittent vertigo, and an epidermoid cyst with unusual T1 and T2 MRI findings, without DWI restriction. Methods: Comparison of this case to a “typical” epidermoid cyst of the posterior fossa imaged with standard MRI including DWI. Results: Our case showed unusual T1 hyperintensity and T2 isointensity, without DWI restriction. Conclusion: Posterior fossa epidermoid cysts typically present with low T1 and high T2 values, with DWI restriction. However, as our case demonstrates, this tumor may present with a rare lack of DWI restriction, and aberrant T1 and T2 values, probably due to unusual protein or blood product components.