Presacral dermoid cyst with scanty fat component: usefulness of chemical shift and diffusion-weighted MR imaging

We present a case of a dermoid cyst located at the presacral space. Although CT and conventional MR (T1- and T2-weighted images) demonstrated a non-specific cystic mass with little evidence of calcification or fat, chemical shift and diffusion-weighted MR imaging suggested the presence of small amount of fat and abundant keratinoid substance within the tumor, respectively. Pre-operative diagnosis of dermoid cyst was made. The tumor was surgically resected and the diagnosis was confirmed. Chemical shift and diffusion-weighted MR imaging are useful in the diagnosis of dermoid cyst with little evidence of calcification and fat.