Cervical cysts in children are mostly of congenital nature with a broad spectrum of clinical presentation and onset time. Some are noticeable with swelling on the neck or oppression symptom not long after birth, some are easily ignored because the perceivable symptoms are found until adult or accompanied with the acute infection. TGDC, BCC, DC and LM are frequent cervical cysts in children, while BC and thymic cyst are rare cases. In our study cohort, we found few cases of BC and no case for thymic cyst. Regardless the cyst subtype, surgical removal is the primary remedy for cervical cysts in children [1]. The surgery should avoid time of acute infection in order to minimize the potential treatment-related damage on blood vessels and nerves [4]. It has been suggested ultrasound-guided sclerotherapy or endoscopic resection provide great benefits for tissue protection or cosmetically consideration [3].
Being different in histological and embryonic initiation, cervical cysts in children are associated with various clinical presentation, occurrence location and onset time.
TGDC is developmental residue derived from thyroid primordium failed to migrate to trachea through Morand’s foramen and commonly resides in anterior neck around the middle line [5]. The neck masses in patients of TGDC often move up and down synchronized with swallow due to the attachment of cysts with hyoid. Previous studies revealed that majority of TGDC onset time is around 5 years old [6]. This agrees with our study cohort in that the median onset time of TGDC is 61 months (Table 1). BCC derives from developmental embryonic anomaly of incomplete closure of branchial cleft. It occurs anywhere from ear lobe to collarbone region and containing four subgroups (first to fourth branchial cleft cysts) [7]. Majority of BCC originated from second branchial cleft, which go along with sternocleidomastoid all the way to tonsillar fossa, coexisting with the path of carotid artery sheath, hypoglossal nerve, glossopharyngeal nerve. Therefore, most of the second branchial cleft cysts reside on the literal side of the neck from submandibular space to supraclavicular space [8]. Data based on our study cohort indicated that all of the BCC cases belong to second branchial cleft cysts and carotid triangle (28/54, 51.9%) is the most frequent occurring space. Enlarged BCC commonly cause asymmetric neck resulting in difficulties in breathing, swallow and vocalization [9]. In our study, 2 (3.7%) BCC patients had hoarse voice, 4 (7.4%) patients presented with snore and sleep apnea and 1 (1.9%) patient had choking, mostly caused by mass oppression to adjacent structures. Although it is well-documented that BCC has no preferential onset age [10], in our study cohort, the median onset time of BCC is 91.5 month, an age significantly older than other types of cervical cysts. This could be a data bias from limited sample size, or implies that BCC has a skewed trend for later onset compared to other neck cysts in children. DC is general terminology for various ectodermic abnormality including dermoid cyst and epidermoid cyst. It often occurs in the regions near mouth floor and hyoid bone. In contrast to TGDC, it does not move together with hyoid bone due to its superficial location. Nevertheless, in clinical practice, it is not uncommon to misdiagnose DC as TGDC before surgery. As exemplified in our study, 19 (25.3%) DC patients were misdiagnosed as TGDC before post-op histopathological evidence being provided. Cervical LM derives from the obstructive embryonic lymph-vessel in neck, mostly around jugular lymph sac. The lesion of LM frequently occurs in occipital triangle and has close association with carotid sheath [11]. In our study, all cervical LM lesions occur in regions of carotid triangle, occipital triangle and supraclavicular triangle, in congruent with previous description [12]. The median onset age of LM in our study cohorts is 41 months but stretch to 140 months. Previous reports revealed that the onset time of LM prevails before 2 years old [13]. The broad distribution of LM patient age in our center is largely because parents or guardians delay in resorting to medical treatment. Enlarged LM, similar[5]to other type of cysts would cause oppression to adjacent structures to block breathing and swallow. Seven (13.7%) LM patients in our study presented with symptom of airway compression (snore/dyspnea). BC develops sporadically (1/42000 ~ 1/68000) from failure in anterior intestine and notochord separation during embryogenesis [14]. Previous study revealed the occurrence peak of BC is below 6 years old for children, and mostly in the neck [15]. It has been reported to occur in multiple regions on the neck including thyroid gland, skin, parapharyngeal space, paratracheal space, soft palate, mouth floor, posterior pharyngeal wall and arytenoid cartilage [14, 16–18]. Interestingly, all of all 9 cases of BC in our study grew in the region of muscular triangle. More often than not, BC manifests as symptomless mass. Similar to other cysts, enlarged BC mass causes snoring, dyspnea and difficulty in swallow, severity of which are determined by the mass size and location [16, 19]. In our study, 5 out of 9 BC patients were symptomless, 4 patients had hoarse voice, snoring or chocking.
Surgical removal currently remains the primary choice for cervical cysts treatment. The present study is the single-center study providing the biggest sample size in the world so far to our best knowledge. The median surgical time in our study is 55 min and the post-op relapse is only 1.8% (7/386), both of which are better than other studies [20, 21]. This could be a result benefiting from the complete removal of the lesions and effective protection of adjacent functional structures during operation. Sistrunk procedure is the main approach for TGDC in our study (97.0%, 191/197), we did in such a way that after resection of the main cysts, we continue to probe and seclude the residue root of the cysts with ligature following the posterosuperior regions of hyoid bone. Nevertheless, some cases still suffered from complications such as swallow pain and slanted tongue due to spreading and extending lesions in a large area. This pinpointed the importance of mindfulness to the anatomy of pharyngeal mucosal structure and the associated blood vessels and nerves in particular lingual artery and hypoglossal nerve during TGDC operation. The lesions in cases of second branchial cleft cysts and LM are generally spreading to a large area. Therefore, beside complete resection of lesions, avoiding make damages to including but not limited to submandibular gland, internal carotid, jugular vein, hypoglossal nerve, submandibular branch of facial nerve would ensure the success of the surgery. Nerve monitors is recommended during the operation in some difficult situations [22]. Bronchogenic cysts are rare and can be treacherous because they reside in deep tissue with latent clinical presentation. Most of the hospitalizations came from the pressure to important functional structures by the prompt enlarged cysts. Surgery should be done as early as possible whenever the cysts has been noticed since delayed treatment would lead to the hideous progressing of this disease. From our study, most of the BCs resided around the trachea and inferolateral region of thyroid gland (66.7%, 6/9). Cysts were often associated with recurrent laryngeal nerve (77.8%, 7/9). Inexperience or incaution may invite damages to recurrent laryngeal nerve and nerve monitor is strongly recommended in surgery.
In our study, 3 TGDC and 4 LM relapsed in all of follow-up cases. Our impression is that the disease recurrence is related to the tissue adhesion from multiple infections and diffused growth of cysts spreading to a large space that makes the complete removal in difficulty.