Lymphoepithelial cysts in the pancreas: MRI of two cases with emphasis of diffusion-weighted imaging characteristics.

Pancreatic lymphoepithelial cysts (LECs) are rare pancreatic cystic lesions filled with keratinized material, lined by mature, keratinizing squamous epithelium and surrounded by lymphoid tissue containing few lymphoid follicles. We report two cases of surgically confirmed pancreatic LECs showing a profound restriction of water molecules on diffusion-weighted (DWI) magnetic resonance imaging (MRI). For pancreatic cystic lesions showing lack of molecular motion on DWI with or without thin marginal enhancement on contrast material-enhanced imaging, LECs consisting of internally keratinized materials with restricted diffusion should be considered in differential diagnoses even though they cannot always be easy to distinguish from other focal pancreatic lesions containing mucin, blood clot, or nonliquefactive necrosis.