Cervical thymic cyst

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A cervical thymic cyst, also called thymopharyngeal duct cyst, is a fluid-filled mass that occurs when the thymopharyngeal duct, an embryonic structure connecting the nascent thymus with the embryonic pharynx, fails to close and disappear. [1] A thymic cyst is typically a solitary mass on one side of the neck, and is usually found near the carotid sheath. [2] Some cervical thymic cysts may extend into the mediastinum. It is usually asymptomatic. [3] The diagnostic process includes differentiating between other causes of neck masses in infants and children, including branchial cleft cysts and cystic hygromas. The treatment is surgical excision. On histologic examination, the wall of the cyst includes thymic tissue, and may include parathyroid gland tissue because of the parathyroid gland's common embryonic origin with the thymus gland in the third pharyngeal pouch. Fewer than 100 cases of cervical thymic cysts have been reported in the medical literature. [2]

Contents

Pathogenesis

Thymus is a lymphoid organ that develops from the 3rd and 4th pharyngeal pouches. [1] [4]

While the pathogenesis of cervical thymus cyst is still unclear, there are two main mechanisms by which this lesion occurs:

  1. Congenital: During the fetal development, the thymus forms from the third branchial pouch which descends lateral to the mediastinum toward the thyroid gland. A remnant of this thymic tissue can persist during its descent through the thymopharyngeal duct, and later on become the cause of the lesion. This mechanism has been better supported by the authorities.
  2. Acquired: The thymic tissue, mainly the Hassall corpuscles and epithelium reticulum, progressively degenerates and ascends upward to cause the lesion. [4] [5] [6]

Clinical Features

Cervical thymic cyst is a very rare pathology that is often incidentally found due to its asymptomatic nature. The patient usually notices a neck mass that grows slowly which triggers them to see a clinician and be admitted to the hospital. [3] However, it can cause symptoms as it grows in size and compresses on other organs. These symptoms include difficulty breathing, difficulty swallowing, hoarseness of voice, among others. [3] [6] [7] It causes neck swelling. [3] Males are more commonly affected. [6] Most cases occur in the first decade of life, as the thymus tends to atrophy after puberty. [3] This lesion usually affects the left side of the neck. [6]

The cyst can be small as 1cm and as large as 26cm. The location can vary as well, from the angle of the mandible to as low as the mediastinum. [6]

Diagnosis

Differential diagnosis

Differential diagnosis include other more common cervical masses, such as branchial cyst, cystic hygroma, dermoid-epidermoid cyst. [6]

This lesion is usually not diagnosed before surgery. Pathology must be obtained for an accurate diagnosis. [3]

Imaging

Ultrasound is used as the first imaging modality, and often shows hypo-echoic, sometimes septated cyst that runs along the sternocleidomastoid muscle.

Other imaging techniques such as CT and MRI can also be used. These are more useful for determining the cyst's relationship to the surrounding structures and planning for the surgery. [3]

The cyst may be uni- or multi-loculated. [6]

Pathology

The wall of the cyst can have multiple array of pathology. It may have single layered squamous cell to multiple layers of stratified cells. Sometimes the sample includes thyroid or parathyroid tissue. This is thought to be due to the common embryologic origin of thymus and thyroid and parathyroid cells. [3]

The cyst itself contains brown colored fluid. [6]

Treatment

Surgery is often the treatment of choice for a complete resection through VATS (Video-assisted thoracoscopic surgery). Because there are important structures surrounding the cyst, such as the carotid sheath, recurrent laryngeal nerve, glossopharyngeal nerve, hypoglossal nerve, and phrenic nerve, the location of the cyst should be carefully established before the operation. [3]

While local resection is usually adequate, thymectomy may be required if there's a suspicion for thymoma or when the cyst is multilocular. [7]

[8]

The prognosis for this type of cyst is considered good. [4] Recurrence is very rare in the post-operative period. [6]

Related Research Articles

<span class="mw-page-title-main">Thyroid</span> Endocrine gland in the neck; secretes hormones that influence metabolism

The thyroid, or thyroid gland, is an endocrine gland in vertebrates. In humans, it is in the neck and consists of two connected lobes. The lower two thirds of the lobes are connected by a thin band of tissue called the isthmus (pl.: isthmi). The thyroid gland is a butterfly-shaped gland located in the neck below the Adam's apple. Microscopically, the functional unit of the thyroid gland is the spherical thyroid follicle, lined with follicular cells (thyrocytes), and occasional parafollicular cells that surround a lumen containing colloid. The thyroid gland secretes three hormones: the two thyroid hormones – triiodothyronine (T3) and thyroxine (T4) – and a peptide hormone, calcitonin. The thyroid hormones influence the metabolic rate and protein synthesis and growth and development in children. Calcitonin plays a role in calcium homeostasis. Secretion of the two thyroid hormones is regulated by thyroid-stimulating hormone (TSH), which is secreted from the anterior pituitary gland. TSH is regulated by thyrotropin-releasing hormone (TRH), which is produced by the hypothalamus.

<span class="mw-page-title-main">Thymus</span> Endocrine gland

The thymus is a specialized primary lymphoid organ of the immune system. Within the thymus, thymus cell lymphocytes or T cells mature. T cells are critical to the adaptive immune system, where the body adapts to specific foreign invaders. The thymus is located in the upper front part of the chest, in the anterior superior mediastinum, behind the sternum, and in front of the heart. It is made up of two lobes, each consisting of a central medulla and an outer cortex, surrounded by a capsule.

<span class="mw-page-title-main">Parathyroid gland</span> Endocrine gland

Parathyroid glands are small endocrine glands in the neck of humans and other tetrapods. Humans usually have four parathyroid glands, located on the back of the thyroid gland in variable locations. The parathyroid gland produces and secretes parathyroid hormone in response to a low blood calcium, which plays a key role in regulating the amount of calcium in the blood and within the bones.

<span class="mw-page-title-main">Parotid gland</span> Major salivary gland in many animals

The parotid gland is a major salivary gland in many animals. In humans, the two parotid glands are present on either side of the mouth and in front of both ears. They are the largest of the salivary glands. Each parotid is wrapped around the mandibular ramus, and secretes serous saliva through the parotid duct into the mouth, to facilitate mastication and swallowing and to begin the digestion of starches. There are also two other types of salivary glands; they are submandibular and sublingual glands. Sometimes accessory parotid glands are found close to the main parotid glands.

<span class="mw-page-title-main">Thyroglossal cyst</span> Medical condition

A thyroglossal cyst is a fibrous cyst that forms from a persistent thyroglossal duct. Thyroglossal cysts can be defined as an irregular neck mass or a lump which develops from cells and tissues left over after the formation of the thyroid gland during developmental stages.

<span class="mw-page-title-main">Ranula</span> Medical condition

A ranula is a mucus extravasation cyst involving a sublingual gland and is a type of mucocele found on the floor of the mouth. Ranulae present as a swelling of connective tissue consisting of collected mucin from a ruptured salivary gland caused by local trauma. If small and asymptomatic further treatment may not be needed, otherwise minor oral surgery may be indicated.

<span class="mw-page-title-main">Cystic hygroma</span> Human disease

A cystic hygroma is an abnormal growth that usually appears on a baby's neck or head. It consists of one or more cysts and tends to grow larger over time. The disorder usually develops while the fetus is still in the uterus, but can also appear after birth.

<span class="mw-page-title-main">Inferior thyroid artery</span> Artery of the neck

The inferior thyroid artery is an artery in the neck. It arises from the thyrocervical trunk and passes upward, in front of the vertebral artery and longus colli muscle. It then turns medially behind the carotid sheath and its contents, and also behind the sympathetic trunk, the middle cervical ganglion resting upon the vessel.

<span class="mw-page-title-main">Superior laryngeal nerve</span> Branch of the vagus nerve

The superior laryngeal nerve is a branch of the vagus nerve. It arises from the middle of the inferior ganglion of vagus nerve and additionally also receives a sympathetic branch from the superior cervical ganglion.

<span class="mw-page-title-main">Mediastinal tumors</span> Medical condition

A mediastinal tumor is a tumor in the mediastinum, the cavity that separates the lungs from the rest of the chest. It contains the heart, esophagus, trachea, thymus, and aorta. The most common mediastinal masses are neurogenic tumors, usually found in the posterior mediastinum, followed by thymoma (15–20%) located in the anterior mediastinum. Lung cancer typically spreads to the lymph nodes in the mediastinum.

<span class="mw-page-title-main">Papillary thyroid cancer</span> Medical condition

Papillary thyroid cancer is the most common type of thyroid cancer, representing 75 percent to 85 percent of all thyroid cancer cases. It occurs more frequently in women and presents in the 20–55 year age group. It is also the predominant cancer type in children with thyroid cancer, and in patients with thyroid cancer who have had previous radiation to the head and neck. It is often well-differentiated, slow-growing, and localized, although it can metastasize.

<span class="mw-page-title-main">Thyroid ima artery</span> Artery of the head and neck

The thyroid ima artery is an artery of the head and neck. It is an anatomical variant that, when present, supplies blood to the thyroid gland primarily, or the trachea, the parathyroid gland and the thymus gland in rare cases. It has also been reported to be a compensatory artery when one or both of the inferior thyroid arteries are absent, and in a few cases the only source of blood to the thyroid gland. Furthermore, it varies in origin, size, blood supply, and termination, and occurs in around 3.8% of the population and is 4.5 times more common in fetuses than in adults. Because of the variations and rarity, it may lead to surgical complications, particularly during tracheostomy and other airway managements.

<span class="mw-page-title-main">Persistent thyroglossal duct</span> Medical condition

A persistent thyroglossal duct is a usually benign medical condition in which the thyroglossal duct, a structure usually only found during embryonic development, fails to atrophy. The duct persists as a midline structure forming an open connection between the back of the tongue and the thyroid gland. This opening can lead to fluid accumulation and infection, which necessitate the removal of the duct.

<span class="mw-page-title-main">Branchial cleft cyst</span> Medical condition

A branchial cleft cyst or simply branchial cyst is a cyst as a swelling in the upper part of neck anterior to sternocleidomastoid. It can, but does not necessarily, have an opening to the skin surface, called a fistula. The cause is usually a developmental abnormality arising in the early prenatal period, typically failure of obliteration of the second, third, and fourth branchial cleft, i.e. failure of fusion of the second branchial arches and epicardial ridge in lower part of the neck. Branchial cleft cysts account for almost 20% of neck masses in children. Less commonly, the cysts can develop from the first, third, or fourth clefts, and their location and the location of associated fistulas differs accordingly.

<span class="mw-page-title-main">Parathyroid adenoma</span> Medical condition

A parathyroid adenoma is a benign tumor of the parathyroid gland. It generally causes hyperparathyroidism; there are very few reports of parathyroid adenomas that were not associated with hyperparathyroidism.

<span class="mw-page-title-main">Parathyroid carcinoma</span> Medical condition

Parathyroid carcinoma is a rare cancer resulting in parathyroid adenoma to carcinoma progression. It forms in tissues of one or more of the parathyroid glands.

<span class="mw-page-title-main">Congenital cartilaginous rest of the neck</span> Medical condition

Congenital cartilaginous rest of the neck (CCRN) is a minor and very rare congenital cutaneous condition characterized by branchial arch remnants that are considered to be the cervical variant of accessory tragus. It resembles a rudimentary pinna that in most cases is located in the lower anterior part of the neck.

Odontogenic cyst are a group of jaw cysts that are formed from tissues involved in odontogenesis. Odontogenic cysts are closed sacs, and have a distinct membrane derived from rests of odontogenic epithelium. It may contain air, fluids, or semi-solid material. Intra-bony cysts are most common in the jaws, because the mandible and maxilla are the only bones with epithelial components. That odontogenic epithelium is critical in normal tooth development. However, epithelial rests may be the origin for the cyst lining later. Not all oral cysts are odontogenic cysts. For example, mucous cyst of the oral mucosa and nasolabial duct cyst are not of odontogenic origin.

Ectopic thymus is a condition where thymus tissue is found in an abnormal location. It usually does not cause symptoms, but may leads to a mass in the neck that may compress the trachea and the esophagus. It is thought to be the result of either a failure of descent or a failure of involution of normal thymus tissue. It may be diagnosed with radiology, such as an ultrasound or magnetic resonance imaging. If it causes illness, surgery can be used to remove it. Recurrence after surgery is very unlikely.

In CT scan of the thyroid, focal and diffuse thyroid abnormalities are commonly encountered. These findings can often lead to a diagnostic dilemma, as the CT reflects nonspecific appearances. Ultrasound (US) examination has a superior spatial resolution and is considered the modality of choice for thyroid evaluation. Nevertheless, CT detects incidental thyroid nodules (ITNs) and plays an important role in the evaluation of thyroid cancer.

References

  1. 1 2 Kaufman, Matthew R.; Smith, Shane; Rothschild, Michael A.; Som, Peter (2001-11-01). "Thymopharyngeal Duct Cyst: An Unusual Variant of Cervical Thymic Anomalies". Archives of Otolaryngology–Head & Neck Surgery. 127 (11): 1357–1360. doi: 10.1001/archotol.127.11.1357 . ISSN   0886-4470. PMID   11701074.
  2. 1 2 Operative Pediatric Surgery. Ziegler, Moritz M., Azizkhan, Richard G., Von Allmen, Daniel, Weber, Thomas R. (2nd ed.). New York. 18 March 2014. ISBN   9780071627238. OCLC   891571895.{{cite book}}: CS1 maint: location missing publisher (link) CS1 maint: others (link)
  3. 1 2 3 4 5 6 7 8 9 Michalopoulos, Nikolaos; Papavramidis, Theodossis S.; Karayannopoulou, Georgia; Cheva, Angeliki; Pliakos, Ioannis; Triantafilopoulou, Konstantina; Papavramidis, Spiros T. (September 2011). "Cervical Thymic Cysts in Adults". Thyroid. 21 (9): 987–992. doi:10.1089/thy.2010.0142. ISSN   1050-7256. PMID   21595559.
  4. 1 2 3 Cigliano, Bruno; Baltogiannis, Nikolaos; De Marco, Marianna; Faviou, Elsa; Antoniou, Dimitrios; De Luca, Ugo; Soutis, Michail; Settimi, Alesandro (2007-10-16). "Cervical thymic cysts". Pediatric Surgery International. 23 (12): 1219–1225. doi:10.1007/s00383-006-1822-5. ISSN   0179-0358. PMID   17938938. S2CID   32159666.
  5. ↑ Strollo, Diane C.; Rosado-de-Christenson, Melissa L. (2012), "Disorders of the Mediastinum", Clinical Respiratory Medicine, Elsevier, pp. 846–861, doi:10.1016/b978-1-4557-0792-8.00071-4, ISBN   9781455707928 , retrieved 2022-01-10
  6. 1 2 3 4 5 6 7 8 9 Shenoy, Vijendra; Kamath, M. Panduranga; Hegde, Mahesh Chandra; Rao Aroor, Raghavendra; Maller, Vijetha V. (2013-02-07). "Cervical Thymic Cyst: A Rare Differential Diagnosis in Lateral Neck Swelling". Case Reports in Otolaryngology. 2013: e350502. doi: 10.1155/2013/350502 . ISSN   2090-6765. PMC   3580929 . PMID   23476854.
  7. 1 2 Wang, Xun; Chen, Kezhong; Li, Xiao; Li, Yun; Yang, Fan; Li, Jianfeng; Jiang, Guanchao; Liu, Jun; Wang, Jun (December 2017). "Clinical features, diagnosis and thoracoscopic surgical treatment of thymic cysts". Journal of Thoracic Disease. 9 (12): 5203–5211. doi: 10.21037/jtd.2017.10.148 . ISSN   2072-1439. PMC   5756969 . PMID   29312727.
  8. ↑ Sturm, Joshua J; Dedhia, Kavita; Chi, David H (2017-01-11). "Diagnosis and Management of Cervical Thymic Cysts in Children". Cureus. 9 (1): e973. doi: 10.7759/cureus.973 . ISSN   2168-8184. PMC   5298914 . PMID   28191377.
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