A 5-year-old girl presents with difficulty breathing. On examination, of the oral cavity a 3 cm mass is found in the midline on the posterior aspect of the tongue. The most likely diagnosis is:

An ectopic thyroid gland can be located anywhere from the base of the tongue to the mediastinum. It often results in the failure of descent resulting in either a linginal thyroid or ectopic thyroid in the midline of the neck. The so called lateral aberrant thyroid is usually a metastasis from papillary carcinoma of the thyroid.Angioneurotic edema is an acute allergic reaction, which causes a sudden swelling of the whole tongue with airway obstruction.