2017 Volume 26 Issue 10 Pages 745-749
We report a case of epidermoid cyst that manifested with unusual radiological findings. A 32-year-old man felt dizzy and a CT scan revealed an extra axial lesion in the front of the left cerebellopontine angle to the medulla oblongata. The lesion showed as hyperdense on CT scan, hyperintense on T1-weighted imaging, and hypointense on T2-weighted imaging. The lesion also showed hypointense on diffusion-weighted imaging. We considered that it contained magnetic resonance and made a preoperative diagnosis of melanocytoma. After surgery, it was confirmed to be an epidermoid cyst. Histological examination found no evidence of either melanin or hemosiderin.
Typicaly, epidermoid cysts’ radiological findings show as a hypodense mass on CT scan, hypointense on T1-weighted imaging, and hyperintense on T2-weighted imaging and diffusion-weighted imaging. But MR imaging signal intensity of epidermoid cysts is varied depending on the protein concentration and the presence of hemorrhage. Owing to those cases where an epidermoid cyst manifests unusual radiological findings, we must always list it as a possible diagnose for an extra axial mass.
