Imaging findings of an epidermoid cyst with malignant transformation to squamous cell carcinoma.

We report imaging findings of a 64-year-old male patient with a ruptured epidermoid cyst (EC) known to be constant over the 23-year followup and showing malignant transformation to squamous cell carcinoma (SCC). Computed tomography (CT) and magnetic resonance imaging (MRI) findings including diffusion weighted imaging (DWI), 1H+MR spectroscopy (MRS), dynamic susceptibility contrast perfusion (DSC) MRI of EC, and its rare complications are presented together with a review of the literature. Fluid-low-attenuated-inversion-recovery (FLAIR) and T1-weighted images with gadolinium are the best sequences together with DWI to show the relationship of the EC, the SCC and the border between. Primary brain SCC enhances mostly ring-like or peripherally, but diffuse enhancement is also possible. To our knowledge, no MRS and DSC findings have been reported in the literature yet. KeywoRds: Epidermoid cyst, Malignant transformation, Intracranial squamous cell carcinoma, Magnetic resonance imaging