Surgical Experiences of Pediatric Cervical Bronchogenic Cysts: A Case Series of 6 Patients

Introduction

Bronchogenic cyst is a rare congenital disease with an incidence of 1 in 42 000 to 68 000 individuals. ¹ Presently, most experts believe that failing of separating foregut from notochord could become a key factor to trigger the foregut duplication. ² Bronchogenic cysts have been reported in infants, children, and adults. The most common sites are the chest and the posterior mediastinum regions, followed by the abdomen ³ and skin.^4,5 Cysts that appear in the cervical area are unusual. ¹ Bronchogenic cysts are often misdiagnosed as the more common congenital neck cysts. To improve the treatment effect of this disease, we retrospectively analyzed the clinical features and treatment outcomes among pediatric patients with cervical bronchogenic cysts.

Patients and Methods

We reviewed all the children with cervical bronchogenic cysts who were treated in Beijing Children’s Hospital affiliated to Capital Medical University in the past 4 years. Six of them who underwent surgical excision were included from January 2016 to December 2019. The clinical features and operative records were reviewed. All patients underwent magnetic resonance imaging (MRI) or computed tomography (CT). The orally chloral hydrate can be used for sedation if necessary.

All patients received surgical treatments, and the recurrent laryngeal nerve (RLN) detector was used during the surgery. The bronchogenic cysts were confirmed by postoperative histopathology examinations. We collected the patients’ information on demographics, diagnosis, and treatment (ie, symptoms, imaging studies, surgical records, and follow-up) for processing.

Results

The retrospective analysis included 6 patients (5 males [83.3%], 1 female [16.7%]; age range: 1 month to 60 months). The clinical data were recorded, including age, presenting symptoms, imaging findings, surgical procedures, and complications (Table 1).

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Table 1.

Bronchogenic Cyst Case Series.

Case	Age	Gender	Symptom	MRI	Site of cartilage	Complication	Recurrence, follow-up, month
1	1 month	F	Mass Dyspnea History of infection	Low T1 High T2	Thyroid cartilage plate (the second operation)	No	Yes 34
2	4 years	M	Mass History of infection	High T1 High T2	Cricoid cartilage	No	No 6
3	5 years	M	Mass	Low T1 High T2	Thyroid cartilage plate	No	No 11
4	5 years	M	Mass	Low T1 High T2	Cricoid cartilage	No	No 15
5	5 years	M	Mass	Low T1 High T2	Cricoid cartilage	No	No 36
6	4 years	M	Mass	Low T1 High T2	Cricoid cartilage	No	No 21

Abbreviations: F, female; M, male.

In the imaging examinations, the cysts appear smooth-edged and close to the airway in all patients. Five cases of bronchogenic cysts showed low signal intensity on T1-weighted image and high signal intensity on T2-weighted image in MRI examination. However, 1 patient showed high TI and T2 signal intensities, which was considered intracapsular hemorrhage after infection.

All of the bronchogenic cysts were resected through an external cervical approach (transverse incision along the skin stripes) under general anesthesia. The RLN detector was used to identify and locate the RLNs during the surgeries. Five patients underwent completely resection, including the chondroid tissues at the base of cysts clinging to the tracheas (Figure 1). The cartilage at the root of the cyst was connected to the cricoid cartilage in 4 cases and was connected to the thyroid cartilage plate in 1 case. During the surgery, the cartilage tissues were removed along the surface of the thyroid cartilage plates or the cricoid cartilages. Only 1 patient recurred because chondroid tissue was not detected in the first operation. The chondroid tissue at the base of the cyst, which was connected to the thyroid cartilage plate, was detected and resected during the second surgery. All cysts were found located inferolateral to the thyroid, and the RLNs were clinging to the side wall of cysts (Figure 2).

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Figure 1.

Complete cyst including the chondroid tissues (arrow) at the base of the cyst.

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Figure 2.

Recurrent laryngeal nerve detected along the lateral portion of the cyst.

Histopathological analysis revealed that the cyst was composed of smooth muscles and seromucous glands lined with pseudostratified ciliated epithelium, which were consistent with bronchogenic cysts.

Case 1: The Recurrent Case

A 1-month-old girl with dyspnea, a history of cervical infection, and the presence of cervical mass was referred to our hospital. The physical examination revealed a mass in her left neck. The CT examination showed that the cyst has smooth edge and close to the airway (Figure 3). Surgical resection was performed in April 2017. During the surgery, the esophagus was located on the surface of the cyst, and the RLN was detected on the medial edge of the cyst. The cyst was removed, and no cartilage tissue was found. The patient reappeared with fever 15 months after discharged from the hospital. A cystic mass in the right neck was detected by ultrasonography and MRI (Figure 4), which confirmed the recurrence. Accordingly, the patient underwent another operation to completely remove the cyst. The chondroid tissue at the base of the cyst, which connected to the right side of the thyroid cartilage plate, was localized and resected during the surgery. The RLN was detected along the lateral portion of the cyst by the detector. No complication occurred and there was no recurrence after the second surgery.

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Figure 3.

Computed tomography of the neck region showing a cystic mass located in the left neck extending to the contralateral side.

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Figure 4.

T1-weighted, magnetic resonance imaging axial view showing low-intensity, well-circumscribed cystic formation in the right side of the trachea.

Case 6: One Typical Case

Case 6 (Table 1) was a 4-year-old boy presenting with an asymptomatic mass in his left neck. His cervical ultrasonography identified a cyst located inferolateral to the thyroid. The MRI examination revealed low TI and high T2 signal intensity lesions with smooth margins around the trachea (Figure 5). The cyst was completely removed by the surgery in May 2018. The RLN clinging to the lateral side of the cyst was separated and protected. The cartilage at the root of the cyst, which was connected to the cricoid cartilage, was resected along the surface of the cricoid cartilage. This case was cured without complications, and there’s no recurrence during the follow-up.

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Figure 5.

T2-weighted, magnetic resonance imaging coronal view showing high-intensity, well-circumscribed cystic formation around the trachea.

Discussion

Bronchogenic cyst is a rare congenital malformation of the ventral foregut. During the third week of pregnancy, the trachea develops from the ventral diverticulum bud of the foregut. Abnormal division and development defects can lead to the formation of bronchogenic cyst during the development of the tracheobronchial tree. ¹ The most common sites are the intrathoracic and the posterior mediastinum regions. ² However, cysts that appear in the neck are very rare. ¹

Bronchogenic cysts in the neck region are usually asymptomatic. Certain symptoms such as dyspnea, cough, and dysphagia may present if the cyst is large. Occasionally, secondary infection may occur. If the cyst is superficial, it may lead to sinus formation and external drainage of purulent substances. If the cyst is deep, it may lead to abscess formation.^6-8 In this study, all patients presented masses in the neck region, and 2 patients had a history of infection, of which a 1-month-old patient showed dyspnea. Because the patient was very young, the cyst enlarged rapidly after infection and compressed her airway.

There are currently no specific imaging standards for bronchogenic cyst. Bronchogenic cysts are usually round or ovoid lesions, with smooth margins, homogeneous density, or with an air-liquid level. If the infection occurs repeatedly, an air-liquid level can be observed on imaging.^5,9 In this study, the cysts were detected around the airway with smooth edges in all patients (Figure 3). The MRI has been proved to be a significant preoperative examination method. Due to the variation in the cyst content, various signal intensities were obtained on T1-weighted images, including protein, hemorrhage, or mucoid materials, while the lesions showed high signal intensity on T2-weighted images.^10-13 In our study, only 1 patient with a history of infection showed high TI and T2 signal intensities on MRI, indicating intracapsular hemorrhage. For the other patients, low signal intensity on T1-weighted images and high signal intensity on T2-weighted images were obtained, indicating water signal.

Definitive diagnosis depends on the histopathology of the surgical specimens. The inner layer of the bronchogenic cyst originates from the respiratory system and covered with a pseudostratified columnar epithelium overlying a fibrous connective tissue wall, which contains the seromucous subcutaneous glands and cartilage plates. ¹ The postoperative pathology analysis were consistent with the above-mentioned cyst characteristics in our study. Due to the risk of complications and malignant transformation, surgical excision is still the choice for the treatment of bronchogenic cysts in the head and neck regions.^14-19 Complete removal of bronchogenic cysts in the head and neck region usually does not recur.^5,19 The complete resection must include the cartilage plates at the base of the cysts. In our study, the cartilage at the root of the cyst was connected to the cricoid cartilage among 4 patients and to the thyroid cartilage plate among 2 patients. There was no recurrence after the cysts and cartilages were completely removed. One child (1-month-old) who recurred after surgery may be due to the difficulty in complete removal of the cartilage tissue at the base of the cyst, resulting in part of the cyst remaining. It can be inferred that the cartilage attached to the airway at the root of the cyst was on the right side. During the first operation, the cyst was observed to extend from the right to the left, and this causes the esophagus to rise. Therefore, it is important to perform complete resection, including the cartilage at the root of the cyst.

Since all the lesions were located around the trachea, and inferolateral to the thyroid, the protection of RLN became particularly important. The RLN is relatively thin in children, and we recommended to use RLN detector to identify and protect the RLN during surgeries. All the RLNs were found clinging to the lateral cysts and were completely separated. There was no hoarseness in any of the patients after surgeries.

Conclusion

Although rare, bronchogenic cysts can occur in the neck region. The possibility of bronchogenic cyst should be considered during the differential diagnosis of peritracheal cystic lesions in children. It is necessary to evaluate preoperative CT or MRI examinations for evaluation. Completely resection of the bronchogenic cysts, including the cartilages at the base, is vital to prevent recurrence. Furthermore, it is critical to protect the RLN closing to the lateral cyst during surgery.