A third branchial pouch cyst presenting as a lateral neck mass in an adult.

Abstract

Anomalies of the branchial apparatus occur with some frequency in the adult and pediatric populations. Branchial anomalies are most often derivatives of the first or second pouch. Branchial anomalies involving the third pouch may present as cysts, sinuses, fistulas, and ectopic glands. They are relatively rare, and they respond well to surgical removal. We report the case of a 53-year-old woman who was referred to us for evaluation of a persistent left upper neck mass. The patient had no history of a cervical mass as a child or young adult. The mass was excised uneventfully, and the final pathology revealed a normocellular parathyroid gland and thymic tissue.

Introduction

The branchial apparatus, which gives rise to a wide array of structures that originate in the cervical area, is organized into pouches, arches, and clefts (figure 1). By the sixth week of intrauterine development, the embryo exhibits paired branchial arches. Each arch is formed by mesenchyme from both somitic mesoderm and neural crest mesoderm. The arches are covered externally by ectoderm and internally by endoderm. Adjacent arches are separated externally by ectodermal branchial clefts or grooves and internally by endodermal pouches. Mesenchyme gives rise to bone, cartilage, and muscle. Each arch has a corresponding branchial artery and nerve.

[FIGURE 1 OMITTED]

The first branchial arch gives rise to mandibular and maxillary processes. These processes contain the cartilage that forms the mandible, the pinna, and parts of the middle ear ossicles--specifically, the head and neck of the malleus and the body of the incus. The first arch also gives rise to the muscles of mastication. The first branchial cleft becomes the external auditory meatus, and the first branchial pouch gives rise to the middle ear and eustachian tube.

The second arch gives rise to an operculum that contains the platysma. The second branchial pouch gives rise to the palatine tonsil and tonsillar fossa. The arch itself gives rise to the handle of the malleus, the long process of the incus, and the stapes superstructure, as well as the styloid process, stylohyoid ligament, lesser cornu, and upper body of the hyoid bone.

The third branchial pouch develops into the inferior parathyroid glands and the thymus. The pouch opens into the pharynx in the region of the piriform sinus.

The superior parathyroid gland and the ultimobranchial body develop from the fourth branchial pouch, also in the vicinity of the piriform sinus.

Developmental anomalies of the branchial apparatus are not uncommon. In fact, they account for 17% of all pediatric cervical masses, and they are the most common type of congenital cervical mass. (1) Branchial remnants are derived from the first arch in 5 to 10% of cases. (1) In 65 to 95% of cases, the anomaly is derived from the second arch. (1) Abnormalities derived from the third and fourth arches are quite uncommon--each less than 5% of the total. (2) According to the most widely accepted theory regarding branchial remnants, branchial cleft anomalies are the result of a persistent branchial apparatus secondary to either (1) an incomplete closure of either clefts or pouches or (2) the failure of the second and fourth arches to obliterate the cervical sinus of His. (2) The failure of a branchial cleft to close results in the development of a persistent sinus tract. Branchial cysts arise from isolated remnants of branchial clefts or branchial pouches. Fistulas form when the mesenchyme separating the cleft and pouch involutes and the cleft and pouch unite. (2)

Like other branchial pouch remnants, third pouch anomalies most frequently present as soft, nontender, well-circumscribed masses on the anterior margin of the sternocleidomastoid muscle. The fistulous tract ascends along the carotid sheath, then posterior to the common carotid artery, then superior to the superior laryngeal, hypoglossal, and vagus nerves; it finally opens into the piriform sinus. (3) Third pouch abnormalities may exist as sinuses, fistulas, or cysts, and most develop on the left side, probably because of the asymmetric development of the branchial apparatus. (4,5) Third and fourth branchial pouch fistulas are collectively referred to as piriform sinus fistulas by many investigators.

Case report

A 53-year-old woman was referred to us for evaluation of a recurrent left neck mass. She had first noticed the mass 3 years earlier, and it had been aspirated and drained at that time. The recurrence had developed only recently. She reported that the mass was not painful and that it had not grown rapidly. She noted no associated symptoms of dyspnea, cough, dysphagia, or throat pain. The patient denied any history of a neck mass as a child or young adult. Except for the previously mentioned needle aspiration, she had undergone no neck procedures.

Examination revealed that the mass was a mobile, firm, nontender, 4-cm nodule at the level of the hyoid bone, anterior to the sternocleidomastoid muscle. No evidence of cervical adenopathy was present. Flexible laryngoscopy revealed normal bilateral vocal fold mobility. The thyroid was irregular with a superficial, anterior, 1-cm mass on the right. The trachea was in the midline, and breath sounds were clear.

Ultrasonography demonstrated a complex cyst in the left neck. Magnetic resonance imaging (MRI) confirmed this finding (figure 2). Findings on fine-needle aspiration biopsy were consistent with a benign cyst.

[FIGURE 2 OMITTED]

The patient was taken to the operating room, where she underwent an uneventful excision of the neck mass. The excised specimen measured 4 x 4 x 1 cm (figure 3). Sectioning revealed that the specimen contained cystic structures filled with yellowish gelatinous material. Other areas were filled with serous fluid. The final diagnosis was a thymic cyst with a normal parathyroid gland (figure 4). The patient did well at follow-up and has since shown no sign of recurrence.

[FIGURES 3-4 OMITTED]

Discussion

Third and fourth branchial abnormalities have been reported in all age groups; they have also been diagnosed in utero. These abnormalities can be especially dangerous in neonates if they rapidly enlarge through a fistulous tract during swallowing. Such an enlargement can lead to tracheal compression and airway compromise. (6) Huang et al reported a case in which a third branchial cleft anomaly presented as a retropharyngeal abscess. (2)

A solitary third or fourth branchial cyst may be contained completely within the thyroid gland and may present as a cold nodule. Such a cyst might be completely intrathyroidal and may be confused with a thyroglossal duct cyst. (7) The signs and symptoms of such a cyst are broad and similar to those of more common disease entities. These symptoms include frequent or recurrent upper respiratory tract infection, neck or thyroid pain, and a neck mass. Other presentations include cellulitis, hoarseness, odynophagia, thyroiditis, abscess, and stridor. Acute suppurative thyroiditis may also be associated with a piriform sinus fistula. (6)

A definitive diagnosis is best reached with multiple imaging modalities because single-modality imaging yields high false-negative rates. Ultrasonography is frequently used to screen neck masses, especially in children; it can identify the presence of gas within the thyroid gland, which is pathognomonic for a piriform sinus fistula. Computed tomography of the neck with intravenous contrast is useful in that it may demonstrate the mass as well as air within the mass. Some investigators believe that the sensitivity of barium-swallow imaging is as high as 80% for diagnosing a piriform sinus fistula, and some have recommended the use of carbonated beverages instead of barium for diagnosis. (8)

The choice of treatment hinges on the relationship of the lesion to the piriform sinus. The treatment for a simple cyst that has no external or internal communication is complete surgical excision, to avoid recurrence. (1,4) Successful treatment of a piriform sinus fistula is more complex. The clinician must visualize the piriform sinus fistula under direct laryngoscopy. This can be accomplished with intubation or injection of methylene blue dye. Neck dissection must then be performed with identification and preservation of the recurrent and superior laryngeal nerves. During the dissection, the involved fibrotic tissue may be removed en bloc with the thyroid specimen. The decision whether to perform hemithyroidectomy will depend on the amount of involved tissue. If a fistulous tract is identified, it should be traced as high as possible and then ligated and excised as high as possible. Recurrence is more likely when thyroid tissue is not removed or when a fistulous tract is not identified. (6) Failure to completely excise a fistulous tract may also result in the development of an esophagocutaneous fistula postoperatively. (9)

In conclusion, the diagnosis and management of third branchial anomalies is challenging. A variety of diagnostic modalities must be employed. Incision and drainage procedures may disrupt tissue planes and render definitive surgical excision more difficult. The treatment for simple cysts is complete excision. Treatment of a piriform sinus fistula requires careful identification of the fistula tract and removal of part of the thyroid gland. The diagnosis of a third branchial remnant is confirmed by identification of the parathyroid and thymus on pathologic review.

References

(1.) Kenealy JF, Torsiglieri AJ Jr., Tom LW. Branchial cleft anomalies: A five-year retrospective review. Trans Pa Acad Ophthalmol Otolaryngol 1990:42:1022-5.

(2.) Huang RY, Damrose EJ, Alavi S, et al. Third branchial cleft anomaly presenting as a retropharyngeal abscess. Int J Pediatr Otorhinolaryngol 2000:54:167-72.

(3.) Ford GR, Balakrishnan A, Evans JN, Bailey CM. Branchial cleft and pouch abnormalities. J Laryngol Otol 1992;106:137-43.

(4.) Edmonds JL, Girod DA, Woodruff JM, Bruegger DE. Third branchial anomalies. Avoiding recurrences. Arch Otolaryngol Head Neck Surg 1997;123:438-41.

(5.) Lin JN, Wang KL. Persistent third branchial apparatus. J Pediatr Surg 1991;26:663-5.

(6.) Liberman M, Kay S, Emil S, et al. Ten years of experience with third and fourth branchial remnants. J Pediatr Surg 2002;37: 685-90.

(7.) Sonnino RE, Spigland N, Laberge JM, et al. Unusual patterns of congenital neck masses in children. J Pediatr Surg 1989;24: 966-9.

(8.) Bar-Ziv J. Pyogenic thyroiditis in children due to a fourth branchial pouch fistula. Pediatr Radiol 1996;26:88-90.

(9.) Burge D, Middleton A. Persistent pharyngeal pouch derivatives in the neonate. J Pediatr Surg 1983;18:230-4.

Daniel D. Charous, MD; Matthew T. Charous, MD; Mary F. Cunnane, MD; Joseph R. Spiegel, MD

From the Department of Otolaryngology--Head and Neck Surgery (Dr. D. Charous and Dr. Spiegel) and the Department of Pathology (Dr. Cunnane), Jefferson Medical College, Thomas Jefferson University, Philadelphia, and the Department of Otolaryngology, University of Michigan School of Medicine, Ann Arbor (Dr. M. Charous).

Reprint Requests: Daniel D. Charous, MD, 4400 N. 32nd St., Suite 220, Phoenix, AZ 85018. Phone: [phone]; fax: [phone]; e-mail: [e-mail]

Originally presented at the Eastern Section Meeting of the Triological Society; Jan. 24-26, 2003; Boston.