OBJECTIVE: To summarize the ultrasonography (US) and magnetic resonance imaging (MRI) findings of lymphoepithelial cysts (LECs) and dermoid cysts (DCs) and to discuss the hyperinternal echo in LECs based on histopathological findings. METHODS: Patients who underwent US and MRI before resection and whose lesions were pathologically diagnosed as LECs or DCs were included (January 2010 to December 2023). Internal echo, convective flow, and Doppler signals were evaluated on US, while on MRI, we measured the apparent diffusion coefficient (ADC). RESULTS: Surprisingly, all lesions (4 LECs and 7 DCs) had hyperinternal echoes. Convective flow and Doppler signals were observed in 2 of the 4 cases of LEC, and the ADC was high in these cases (2.4 × 10 CONCLUSION: It is well known that DCs appear hyperechoic on US owing to the presence of keratin
however, it is necessary to recognize that some LECs are depicted as hyperechoic masses and have convective flow and Doppler signals depending on the content.