Familial thyroglossal duct cyst

Other Names: Hereditary thyroglossal duct cysts; Thyroglossal duct cysts; Thyroglossal duct cysts familial Familial thyroglossal duct cyst is a rare hereditary form of a benign congenital neck mass, known as a thyroglossal duct cyst (TDC). TDC is the most common congenital midline neck mass in the pediatric population. They usually present in children, around 6 years of age, but rarely, they may present in adulthood. They present as a painless, palpable mass that develops around the midline and moves with swallowing.

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Cause

Thyroglossal duct cysts (TDCs) are caused by abnormal development and migration of the cells forming the thyroid gland between the 4th and 8th week of fetal development. The thyroglossal duct is the area in which the cells that form the thyroid gland migrate during fetal development. It typically closes off and dissolves before birth, but may remain open in some individuals. When the thyroglossal duct fails to dissolve completely, a cyst (fluid filled sac) may form. It is not clear why occurs in some individuals. While most cases are sporadic; there are reports of at least six families in which TDC appear to be hereditary. The underlying genetic cause of familial TDC is not known.

Inheritance

The cause of this abnormal development is largely not known and usually sporadic; however, in rare circumstances TDCs can be inherited .Familial TDC are commonly inherited in an autosomal dominant pattern with rare reports of autosomal recessive inheritance.

Epidemiology

Thyroglossal duct cysts (TDC) are the most common congenital midline neck mass. Thyroglossal duct remnants occur in approximately 7% of the population, although only a minority of them ever cause symptoms.Familial TDC is more rare. Based on limited case reports published in the medical literature, approximately 21 patients from 7 families have been identified with familial TDC.

Signs and symptoms

Thyroglossal duct cysts most often present with a palpable asymptomatic midline neck mass usually below [65% of the time] the level of the hyoid bone. The mass on the neck moves during swallowing or on protrusion of the tongue because of its attachment to the tongue via the tract of thyroid descent. Some patients will have neck or throat pain, or dysphagia.

The persistent duct or sinus can promote oral secretions, which may cause cysts to become infected. Up to half of thyroglossal cysts are not diagnosed until adult life. The tract can lie dormant for years or even decades, until some kind of stimulus leads to cystic dilation. Infection can sometimes cause the transient appearance of a mass or enlargement of the cyst, at times with periodic recurrences. Spontaneous drainage may also occur. Differential diagnosis are ectopic thyroid, enlarged lymph nodes, dermoid cysts and goiter. They present as a painless, palpable mass that develops around the midline and moves with swallowing. Other symptoms might include: fluctuation in size of mass, dysphagia, infection of mass, and mid-neck tenderness.

Diagnosis

Diagnosis of a thyroglossal duct cyst requires a medical professional, and is usually done by a physical examination. It is important to identify whether or not the thyroglossal cyst contains any thyroid tissue, as it can define the degree of cyst that is being dealt with.

Diagnostic procedures for a thyroglossal cyst include:

• Blood Test:Blood testing of thyroid function.
• Ultrasound:Image capture of the degree of mass and its surrounding tissues.
• Thyroid Scan:Radioactive iodine or technetium (a radioactive metallic element) is used in this procedure to show any abnormalities of the thyroid.
• Fine Needle Aspiration:The removal of cells for biopsy, using a needle

Treatment

Surgical excision is the treatment of choice for uncomplicated thyroglossal duct cysts. The Sistrunk procedure is typically performed, which can reduce the risk of recurrence. This involves removing the cyst as well as a portion of the hyoid bone (small bone in the upper neck) and some tongue tissue. Researchers are looking into the efficacy of ethanol sclerotherapy, in which ethanol, a type of alcohol, is injected into the cyst. While results are promising, surgery remains the primary treatment method.

NIH genetic and rare disease info

• NIH info on Familial thyroglossal duct cyst

Familial thyroglossal duct cyst is a rare disease.

Familial thyroglossal duct cyst Resources
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