Unusual MRI appearance of a lymphoepithelial cyst in the parotid gland

Lymphoepithelial cysts, which are also known as branchial cleft cysts, commonly occur in the lateral cervical region. Lymphoepithelial cysts arising in the parotid gland are rare and must be distinguished from parotid gland tumors. Magnetic resonance imaging (MRI) is useful for diagnosing parotid gland lesions, and MR images of lymphoepithelial cysts typically display a cystic mass that appears homogeneously hypointense on T1-weighted images and homogeneously hyperintense on T2-weighted images. However, some parotid gland tumors that retain fluid in their inner sections show similar MRI findings to lymphoepithelial cysts. Furthermore, lymphoepithelial cysts are sometimes modified by inflammation, and these cases are hard to diagnose. We report the case of a 59-year-old female with a lymphoepithelial cyst that arose in the parotid gland. The cyst had been affected by inflammation and displayed atypical imaging findings, i.e., heterogeneous signal intensity of the liquid component and the presence of a well-enhanced capsule-like structure surrounding the liquid component. In addition, we compare the MRI findings of this case with those of two other cervical lymphoepithelial cysts.