Cystic hygroma of the parotid gland.

Cystic hygroma of the parotid gland is an uncommon benign congenital neoplasm that presents as an asymptomatic soft fluctuant mass. Cervical ultrasonography, computerized tomography (CT) and magnetic resonance imaging (MRI) are used to assess the size and extent of the lesion and to assist in planning the surgical approach. Ultrasonography may demonstrate a multilocular cystic mass containing septa of variable thicknesses. Extension of the mass into deeper structures is more accurately assessed by CT or MRI. A CT scan may show thin-walled cystic masses filled with material of density close to that of water. The use of contrast medium can demonstrate the relationship of the lesion to the surrounding structures. Magnetic resonance imaging is superior to CT in defining the nature and extent of the lesion.