Ultrasonographic appearance of dermoid and epidermoid cysts in the head and neck.

The ultrasonographic features of 6 histologically proven dermoid and epidermoid cysts in the head and neck are reported. All 6 cysts had internal echoes, with a solid appearance. Five of the 6 were echogenic, with only slight or no posterior echo enhancement. Amorphous keratinous debris from keratinizing stratified squamous epithelium filled the lumen of each cyst, producing the internal echoes. Most of the true solid tumors examined were generally of lower echogenicity, and could be differentiated from dermoid and epidermoid cysts ultrasonographically, although lipomas were indistinguishable from these cysts.