Table II.

Indications on when to use different imaging techniques and iconographic features of epidermoid cysts.

	Indications	Characteristics of epidermoid cyst
US	First-line imaging method to detect the lesion and to formulate the main diagnostic hypothesis	Cystic well-defined lesions with variable imaging features: homogeneous hypoechoic content, hypoechoic with some hyperechoic spots, or hyperechogenic aspect. No vascularisation with colour Doppler
CT	Only if MRI is not available	Homogeneously hypodense or hypodense with hyperdense components. Sometimes with post-contrast peripheral enhancement
MRI	Second level diagnostic investigation, best imaging method to evaluate the location of the cyst and establish the surgical planning, in consideration of the position between the geniohyoid and mylohyoid muscles	Well-circumscribed, non-enhancing, cystic lesion, with homogeneous content hyperintense on T2w and iso-hypointense on T1w images, without restriction of water molecule diffusion. No signal suppression in fat-saturated images