[Uncommon sonographic findings of an epidermoid cyst in the head and neck].

Epidermoid cysts are rare lesions in the head and neck. Most often the are located in the submental region, although they sometimes can impose certain diagnostic problems. We report the case of a 19-year-old girl who presented with a fluctuant, painless, midline swelling of the floor of her mouth that had persisted for three months. Ultrasonographic examination showed a 5 x 5 x 4 cm cystic tumor with the unusual aspect of multiple smaller spherical formations. The differential diagnosis of the lesion included dermoid cysts, epidermoid cysts, ranula and parasitic lesions. Computed tomography and magnetic resonance tomography were not diagnostic. The patient underwent excision of the lesion, during which the cyst was completely removed. Histopathological diagnosis was consistent with an epidermoid cyst. The striking sonographic aspect of multiple spherical formations in the lesion was caused by multiple spherical keratin formations.