Volume 5, Issue 4 , Pages 170-173, December 2010
Thyroid abscess with branchial anomaly
Article Outline
- Abstract
- 1. Introduction
- 2. Case report
- 3. Discussion
- 4. Conclusion
- Conflicts of interest
- References
- Copyright
Abstract
The third arch branchial fistula is a rare congenital abnormality that presents as an inflammatory process in the anterior neck, often in the region of the left lobe of thyroid. Incomplete fistula is not an uncommon finding extending from base of pyriform sinus to the thyroid or perithyroidal space, which predisposes to recurrent suppurative thyroiditis during episodes of upper respiratory infection. Complete fistula of third arch is extremely uncommon, especially of congenital origin. A 10-year-old male child presented with a small opening in the anterior neck since birth, with a swelling around it. Computerized tomography revealed a patent tract from neck skin to base of pyriform sinus. Total excision of the tract up to the left pyriform sinus with hemithyroidectomy was performed. There was no recurrence at 22 months of follow-up.
Keywords: Branchial arch, Abscess, Fistulography, Thyroid, Excision
1. Introduction
Branchial apparatus consists of five pairs of mesodermal arches, which are separated by endodermal and ectodermal pouches / clefts. Branchial fistula is formed following the rupture of the interposing branchial plate [1]. More than 90 percent of branchial anomalies arise from the second arch and 8 percent from the first arch. Third and fourth branchial arch anomalies, though rare usually present as sinuses/incomplete fistulas of pyriform sinus or as recurrent suppurative thyroiditis [2]. Complete fistula of branchial apparatus is extremely rare [2], [3]. We hereby report a case of congenital third branchial arch fistula with a cervical skin opening.
2. Case report
A 10-year-old male child presented with history of painful swelling on the left side of anterior neck with intermittent mucoid discharge, which increased on taking food for one week duration. He gives history of similar complaints one year ago. There was no history of spontaneous rupture, trauma or surgery. There was no history of dysphagia, hoarseness of voice, halitosis, recurrent cough or respiratory distress. He had no other opening or swelling in the neck. There was no significant family history.
On examination, a 1
mm diameter opening was noticed on the middle third of the anterior neck 2cm left of midline (Fig. 1). The skin around was hyperpigmented with mild erythema and edema. The opening of the tract was moving with swallowing but not on protrusion of tongue. The rest of the physical examination was unremarkable. Patient was started on intravenous antibiotics and given for two weeks. After the inflammation subsided, computerized tomography and fistulography showed a patent fistulous tract extending from the cervical skin (Fig. 2) through the left lobe of thyroid gland (Fig. 3) to the left pyriform sinus, where spillage of contrast was noted (Fig. 4). No other significant abnormality was detected in the neck. Ultrasonography revealed a heterogenous, hypoechoic area involving the soft tissues of anterior neck at the level of thyroid on the left side. Direct hypopharyngoscopy showed an opening at the lateral wall of pyriform sinus and not at the apex. Thyroid function tests were normal. Iodine-131 scan revealed decreased uptake on the left lobe of thyroid.
Fig. 1.
Clinical photograph of third branchial fistula in which the external skin opening was noticed on the middle third of the anterior neck 1.5
cm left of midline.
Fig. 2.
Computerized tomography following contrast injection externally reveals the collection of the material just beneath skin opening.
Fig. 3.
Computerized tomography showing the passage of contrast along the tract which passes through the left lobe of thyroid following external injection.
Fig. 4.
Computerized tomography revealing the spillage of the contrast into the pyriform sinus following injection through the external opening in neck.
Under general anesthesia, a transverse elliptical incision was made around the external opening and dissected carefully on either side of the tract. The tract went through the left lobe of the thyroid gland up to the superior pole. Left hemithyroidectomy was performed in continuous with the tract. At this stage, under rigid laryngoscopic guidance, 1% methylene blue was injected into the aperture of pyriform sinus. This made the localization of the tract easier during dissection (Fig. 5). The tract passed behind the common and internal carotid arteries to enter thyrohyoid membrane above hypoglossal nerve and opened into the base of pyriform sinus. The entire tract was excised up to the pyriform sinus (Fig. 6). Deeper pharyngeal mucosal defects were closed efficiently with purse string suture, and the muscle layers were strengthened-sutured to avoid pharyngeal leakage. A suction drainage tube was inserted and kept for 48hours. Postoperative course was uneventful. The pathological findings showed a hyperplastic epidermis with acute and chronic inflammation with ulceration and extensive granulation tissue replacing the dermis. After 22 months of follow-up, the patient showed no recurrence.
Fig. 5.
Appearance of 1% methylene blue in the tract following its injection into the aperture of pyriform sinus under rigid endoscopic guidance, after left hemithyroidectomy in continuous with the tract, made the localization of the tract easier during dissection.
Fig. 6.
Specimen of the third branchial fistula excision up to pyriform sinus, coupled with left hemithyroidectomy.
3. Discussion
Ascherson (1832) first gave the description of branchial cleft lesion [4]. In 1933, Raven described an incomplete fistula of third branchial arch in a neonate with left cervical swelling [4], [5], [6]. Miyauchi et al. made the first clinical observation that pyrifrom sinus fistula might cause suppurative thyroiditis in infants and children [6]. Third and fourth arch cysts and fistulas are very rare [1], [4]. They are formed during the fifth week of gestation when the 2nd arch enlarges and grows over 2nd, 3rd, and 4th clefts forming an ectodermal depression called cervical sinus. Failure of complete obliteration of the sinus results in branchial cyst formation. During embryological development, the third and fourth pharyngeal pouches are connected to the pharynx by the pharyngobranchial duct, which degenerates by seventh week. Persistence of this duct results in formation of a sinus tract that communicates with pyriform sinus [1], [7].
The course of third branchial fistula presumably originates from the cephalic region of pyriform fossa, anterior to fold made by internal laryngeal nerve [4], [5], like in our case. It then pierces the thyrohyoid membrane cranial to superior laryngeal nerve and passes over the hypoglossal nerve to course behind the internal carotid artery and superficial to superior laryngeal nerve, to pass through the platysma to terminate, commonly along the anterior border of sternocleidomastoid at the junction of upper two-third and lower third of neck [2], [5]. In our case the tract followed the above course to pass through the left lobe of thyroid gland, to terminate on the left neck.
The fourth branchial fistula follows a “2-loop course”, originating from the caudal end of the pyriform fossa, posterior to fold made by internal laryngeal nerve, coursing inferiorly along the tracheo-esophageal groove, posterior to thyroid gland into the mediastinum, to loop around the aorta (left side) and subclavain artery (right side). It then ascends cephalad to pass over hypoglossal nerve before piercing the platysma to end on the cervical neck [1], [4], [5].
Third and fourth branchial arch anomalies have been described in all age groups, even in utero. Clinical presentation depends on the mass effect and respiratory compromise in neonates or recurrent infections secondary to persistent sinus tracts in older patients [5], [7].
These anomalies could be fatal in neonates due to the risk of enlargement of these tracts during swallowing resulting in tracheal compression and airway compromise [2], [7].
Left sided predominance of these lesions could be due to either asymmetrical derivatives of the branchial arch or suppressed embryogenesis of ultimobranchial body on the right side [1], [5].
The external sinus opening or pseudofistula may develop at the site of previous surgical drainage, rupture or incomplete excision [3]. In our case, no such history was present, thus confirming the congenital nature of the cervical neck opening at an unusual site. Since the external opening site was at the level of the left lobe of thyroid, intrauterine rupture of the cervical cyst of branchial origin could be thought of.
Barium swallow is diagnostic and must be performed in any suppurative inflammation of neck of unknown origin in which the tract may not be delineated clearly due to the presence of active infection, wherein CT scan would be a better choice. Repeat swallow during quiescence could be useful in such circumstances [5], [8].
CT scan following barium swallow or contrast injection through the cannulated external opening would be more useful in delineating the entire tract than plain CT scan alone [5]. However, presence of air near the lesser horn of thyroid cartilage in CT scan may be considered pathognomonic even during inflammation but this sign is inconstant [8].
In our case, cannulating the fistulous opening followed by contrast injection and CT scanning provided an excellent delineation of the entire tract with spillage of contrast into left pyriform sinus.
Moreover, the use of modified Valsalva and Trumpet maneuvers during CT scan and ultrasonography make use of air as a contrast in delineating the course of the tract [4], [5]. Airfluid levels within the thyroid gland or surrounding soft tissues may suggest abscess formation [5]. Direct laryngoscopic examination and visualization of the internal pyriform sinus opening with cannulation may also be used for diagnosis [5], [8].
Total excision of the tract with partial or hemithyroidectomy during the quiescent period is the treatment of choice [1], [2], [3], [4]. Adequate exposure may be provided by Woodman's approach or by retracting/ excising a vertical strip of posterior border of thyroid ala. Some investigators agree that complete disconnection of the tract from the pyriform sinus at the level of thyrohyoid membrane is sufficient [5]. Intraoperative cannulation with or without injection of 1% methylene blue into the pyriform sinus opening under endoscopic or laryngoscopic guidance can be effective in localizing the course of tract [3], [4]. Postoperative complications are more common in children less than 8 years of age and include temporary vocal cord paralysis, salivary fistula and wound infection [4]. Recurrence is possible after many years of surgery, usually following inadequate excision and during acute episode of suppurative thyroiditis. Hence long term follow-up may be necessary [5]. Recently, chemocauterization with trichloroacetic acid has been reported. Some authors suggest endoscopic electrocauterization and endoscopic fibrin glue after simple cervical drainage [2], [7], [8].
4. Conclusion
Third branchial arch anomalies are very rare; however it presents as cervical infection, often in the region of the left thyroid lobe. It is associated with a communicating tract extending from base of pyriform sinus to the thyroid or perithyroidal space, which predisposes to recurrent suppurative thyroiditis during episodes of upper respiratory infection. In our case, a cervical opening was present since birth with two episodes of suppurative thyroiditis so far including the present one. Diagnosis can be confirmed by CT scan, barium swallow during quiescence and direct laryngoscopy. Third and Fourth arch fistula should be differentiated by their different course. Total excision of the tract with partial or hemithyroidectomy should be performed carefully to prevent recurrence.
Conflicts of interest
None.
References
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PII: S1871-4048(09)00057-4
doi:10.1016/j.pedex.2009.09.004
© 2009 Elsevier Ireland Ltd. All rights reserved.
Volume 5, Issue 4 , Pages 170-173, December 2010
