The following statements about thyroglossal cyst are true, except .
**Core Concept**
A thyroglossal cyst is a congenital anomaly resulting from the abnormal persistence of the thyroglossal duct, which is a structure that forms during embryonic development and normally regresses after the formation of the thyroid gland. This cyst can contain thyroid tissue, but it is not a true thyroid gland.
**Why the Correct Answer is Right**
The thyroglossal duct is a remnant of the thyroglossal duct cyst, which is a developmental anomaly that occurs during the 6th to 8th week of embryonic development. The thyroglossal duct is formed by the downward migration of the thyroid gland from the base of the tongue to its final location in the neck. In most cases, the thyroglossal duct regresses, but in some cases, it persists and forms a cyst. This cyst can contain thyroid tissue, but it is not a true thyroid gland. The Sistrunk procedure, which involves the removal of the cyst, the central part of the hyoid bone, and the tract leading up to the foramen cecum, is the standard treatment for thyroglossal cysts.
**Why Each Wrong Option is Incorrect**
**Option A:** This statement is incorrect because thyroglossal cysts are not typically pre-auricular or near the angle of the mandible. They are usually located in the midline of the neck, near the hyoid bone.
**Option B:** This statement is incorrect because thyroglossal cysts can contain thyroid tissue, but they are not a true thyroid gland. They are a congenital anomaly that results from the abnormal persistence of the thyroglossal duct.
**Option C:** This statement is incorrect because the Sistrunk procedure is the standard treatment for thyroglossal cysts, not thyroglossal duct cysts. While the terms are often used interchangeably, the Sistrunk procedure specifically refers to the surgical removal of the cyst, the central part of the hyoid bone, and the tract leading up to the foramen cecum.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that thyroglossal cysts can contain thyroid tissue, but they are not a true thyroid gland. This is a key distinction, as the treatment for thyroglossal cysts is different from that of a true thyroid gland.
**Correct Answer: B. Thyroglossal cysts are a true thyroid gland.**