<prompt> Child with midline swelling in the neck most probable diagnosisThyroglossal cystThyroidCystic hygromaDermoid cyst  <response>: Ans. a Thyroglossal CystRef: Schwartz 10th edition, Page 1602 Midline masses include thyroglossal duct remnants, thyroid masses, thymic cysts, or dermoid cysts Thyroglossal cysts account for about 75 of congenital midline swellings in childhood, and they are the most common abnormality of the midline neck seen in children 