sentences:  For masses presenting in adulthood, the presumption should be a malignancy until proven otherwise, since carcinomas of the tonsil, tongue base and thyroid may all present as cystic masses of the neck.Unlike a thyroglossal duct cyst, when swallowing, the mass should not move up or down.Four branchial clefts (also called "grooves") form during the development of a human embryo.