Congenital familial bilateral branchial tracts: a rare case.

Abstract

The embryologic development of the head and neck is directed by an ensemble of numerous genes. Embryologic malformations of the head and neck are rare. When they do occur, the most common are thyroglossal duct cysts and branchial anomalies. Most malformations are apparent at birth. Complete excision at an early stage is recommended to prevent complications such as infection. We describe an extremely rare case of bilateral branchial tracts in which there was evidence of a genetic etiology. To the best of our knowledge, this is the first case of familial bilateral branchial tracts to be described in the literature.

Introduction

During fetal development, structures between the head and heart arise from the branchial apparatus. Of the six branchial arches in humans, the fifth and sixth are rudimentary. (1) The development of many structures in the head and neck is immediately related to either the branchial arches or the pharyngeal pouches. (2) The makeup of these embryologic structures is transient, as they undergo remodeling to the point that their original forms are essentially unrecognizable in adults.

Members of the Antennapedia class of homeobox genes, known as Hox genes, are believed to be pivotal in regulating vertebrate craniofacial development and controlling morphogenesis and the growth of the proximal-distal axis. (3,4) In 1997, Vieille-Grosjean et al showed for the first time that at 4 weeks of development, human branchial arches express the paralogous groups using the mouse homologues of HOXB1, HOXA2, HOXB2, HOXA3, HOXB3, HOXD3, HOXB4, and HOXC4 as probes for in situ hybridization. (4)

These authors demonstrated the importance of combinatorial expression patterns of genes in the craniofacial development of humans. (4)

Hox genes act in synergy and in different temporal patterns, and no single function can be ascribed to a single gene. For example, 700 genes determine the structure and function of the organ of Corti alone. To date, no correlation has been observed between the genetic background and embryologic branchial arch malformations.

Aberrations in branchial arch development can cause branchial malformations. During closure of the cervical sinus that lies between the second branchial arch and the epipericardial ridge, ectoderm may become trapped, resulting in the formation of an inclusion or cyst. These are known as branchial cysts or sinuses, which lie on the lateral neck anterior to the sternocleidomastoid muscle. (2)

The phrase branchial cleft anomaly is not an accurate one. The term cleft implies that all branchial malformations are derived solely from a branchial cleft without any contribution from the corresponding pouch or arch. (5) Therefore, the phrase branchial anomaly is preferred.

A fistula has an opening to both gut and skin, while a sinus tract is open to either but not both. (6) A cyst is a closed structure with no connection to either. (6) Histologically, branchial sinuses are lined by pseudostratified columnar epithelium with lymphoid tissue; in rare cases, salivary tissue or sebaceous glands are also present. (5)

Nicollas et al described the prevalence of different embryologic malformations of the neck in 191 children. (7) Malformations of the midline included 102 cases of thyroglossal duct cyst (53.4% of all cases) and 21 cases of dermoid cysts (11.0%). The most common malformations of the laterocervical region were 37 cysts and fistulas of the second deft (19.4%), 20 of the first cleft (10.5%), 7 of the fourth pouch (3.7%), and 4 thymic cysts (2.1%). (7) Embryologic anomalies of the fourth branchial pouch are rare. They usually present as recurrent episodes of deep neck infections during early childhood. In a review of fourth branchial pouch anomalies published in 2004, Jeyakumar and Hengerer described 3 cases; 2 of these patients presented as adults with recurrent deep neck infections, and the other, a 14-year-old boy, presented with a sore throat after he had swallowed a large pill. (6)

[FIGURE 1 OMITTED]

A fourth branchial fistula has a cutaneous orifice that is identical to the orifices of the second and third branchial fistulae. The orifice of the fourth branchial fistula lies along the anterior border of the sternocleidomastoid muscle during development. The branchial tract then courses superiorly over the hypoglossal nerve and descends posteriorly to the common carotid artery. Then it loops posteriorly around either the aortic arch on the left or the subclavian artery on the right. The tract then ascends lateral to the trachea and terminates at the apex of the piriform sinus? The cutaneous orifice of the third branchial fistula also opens anterior to the sternocleidomastoid muscle, but it courses only superiorly, passing posterior to the common or internal carotid artery, superior to the hypoglossal nerve, and inferior to the glossopharyngeal nerve. The tract pierces the posterolateral thyrohyoid membrane and enters the piriform sinus more anterior and cranial than does the fourth branchial fistula?

In this article, we describe an extremely rare case of asymptomatic bilateral branchial tracts in which there was evidence of a generic etiology. To the best of our knowledge, this is the first case of familial bilateral branchial tracts to be described in the literature.

Case report

A healthy 49-year-old white woman presented to the University of Nebraska Medical Center in Omaha with mucous discharge from congenital bilateral branchial tracts. The openings were located along the anterior border of the sternocleidomastoid muscle, 2 cm superior to the clavicle (figure 1). The left anomalywas more prominent, and mucus could be expressed from it more easily.

The patient reported a family history of branchial tracts in her sister and in 3 male cousins (figure 2). Her sister's anomaly, which was also congenital and bilateral, was treated at age 27 with complete surgical excision. Her 3 cousins all had congenital defects suggestive of branchial tract anomalies; 2 of them underwent surgical excision, but nothing further was known about their cases. The cousins' father (i.e., the patient's uncle [her blood relative]) was unaffected. The cousins' mother (the patient's aunt by marriage) might or might not have been affected; her personal and family history were unknown. The patient's own 3 children were unaffected.

[FIGURE 2 OMITTED]

The patient reported no complications such as infections or fullness except for one episode of a severe respiratory tract infection a few years earlier; at that time, she said her lymph nodes felt swollen and her tracts felt like "hard strings" extending cranially to the mandibular angle.

The patient was referred to the otolaryngology outpatient clinic for further examination. She was completely healthy and had no acute or chronic complaints. No indurations were palpable. The patient said that she could express clear viscous mucus from the left tract once a week and from the right tract only once every 4 months.

A radiologic investigation with barium contrast swallow was performed to define the anatomy of the branchial anomalies and to detect a possible connection to the piriform sinus or parapharyngeal space. Also, fistulograms were obtained with a 3.5-gauge angiogram catheter that had its wire support removed. In the smaller tract on the right, a high degree of resistance was present, and the water-soluble contrast medium was not able to enter the tract; the opening could not be cannulated. On the left, the catheter was introduced easily into the opening, and the water-soluble contrast medium opacified the tract (figure 3). The tract extended directly cranially from the opening in the paramedian axis at a length of 7 cm. Injection of additional contrast material (total volume: ~40 ml) resulted in bulging of the tract. No connection to the pharynx was seen. The tract terminated at the level of the mid-piriform sinus. The patient experienced one episode of coughing during a contrast injection, but she did not report any taste or sensation of fluid. She did report a pressure sensation.

[FIGURE 3 OMITTED]

The patient did not wish to undergo any surgical excision or further exploration of the tracts.

Discussion

The radiographic findings in this case were consistent with a third branchial arch anomaly. A fourth branchial arch anomaly was ruled out because of the tracts direct cranial course. First and second branchial arch anomalies were excluded because of their very different course and location.

The induration of the tracts that the patient had experienced during the upper respiratory tract infection might have been caused by the reactive hyperplasia of lymphoid tissue within or adjacent to the tracts or by an increase in mucosal secretion from the goblet cells of the lining epithelium. Regular secretions may be emitted as mucus from goblet cells in the mucosal lining of the ducts or as saliva from the pharynx. The latter was ruled out in our patient because we found no connection to the pharynx.

Our patient's strong family history is suggestive of a genetic abnormality, possibly the result of an aberration in the combinatorial expression pattern of the Hox genes.

Most cases of branchial abnormalities are apparent at birth. Complete excision early on is recommended to prevent complications such as infection. However, our patient did not wish to undergo any intervention, and since she was free of any complaints, we did not feel any need to adhere to this recommendation.

We hope that our description of this rare case raises awareness of embryologic branchial malformations. The fact that there may be an underlying genetic basis for these malformations may open a new field of early diagnostics and possible therapy. Future investigations of branchial tracts should focus on embryologic molecular genetics, especially with respect to the Hox genes.

Acknowledgment

We thank William M. Lydiatt, MD, for his helpful comments on the manuscript.

References

(1.) Patten BM. Human Embryology. 3rd ed. New York: McGraw-Hill; 1968:335-44.

(2.) Cummings CW. Neck anatomy. In: Cummings CW, Fredrickson JM, Harker LA, et al. Otolaryngology-Head and Neck Surgery. St. Louis: Mosby; 1986:1582-86.

(3.) Favier B, Dolle P. Developmental functions of mammalian Hox genes. Mol Hum Reprod 1997;3(2): 115-31.

(4.) Vieille-Grosjean I, Hunt P, Gulisano M, et al. Branchial HOX gene expression and human craniofacial development. Dev Biol 1997; 183(1):49-60.

(5.) Nguyen T. Branchial cleft cysts. Baylor College of Medicine. http://www.bcm.edu/oto/grand/71097.html. Updated Feb. 13, 2006. Accessed Nov. 15, 2007.

(6.) Jeyakumar A, Hengerer AS. Various presentations of fourth branchial pouch anomalies. Ear Nose Throat J 2004;83(9):640-2, 644.

(7.) Nicollas R, Guelfucci B, Roman S, Triglia JM. Congenital cysts and fistulas of the neck. Int J Pediatr Otorhinolaryngo1 2000;55(2): 117-24.

(8.) Zadvinskis DP, Benson MT, Sore PM, SmokerWR. Embryology and congenital cystic lesions. In: Som PM, Curtin HD, eds. Head and Neck Imaging. 3rd ed. Vol. 2. St. Louis: Mosby; 1996:747-56.

Julia Vent, MD, PhD; Candace G. Grier, MD; Donald A. Leopold, MD; Barbara B. Heywood, MD

From the Department of Otolaryngology-Head and Neck Surgery (Dr. Vent, Dr. Leopold, and Dr. Heywood) and the Department of Radiology (Dr. Grier), University of Nebraska Medical Center, Omaha.

Corresponding author: Julia Vent, MD, Department of Otorhinolaryngology-Head and Neck Surgery, University Hospital of Cologne, Kerpener Str. 62, 50924 Cologne, Germany. Phone: [phone]; fax: [phone]; e-mail: [e-mail]