2001-12-.4-15 Vallecular cyst © Cuillier www.thefetus.net/
Fabrice Cuillier, MD, Jacques Bidault, MD
From the department of Obstetrics and Gynecology, Hôpital Félix Guyon, rue des Topazes, 97400 Saint-Denis, Reunion Island, France. Ph : 0262 90 55 22. Fax : 0262 90 77 30.
Definition : Laryngeal cysts are uncommon in children. Aryepiglottic cyst is the most common laryngeal cyst in children, followed by vallecular cyst (VC), ventricular cyst and subglottic cyst. Although these cysts are benign, they may cause serious airway obstruction and even death if not treated appropriately. A mortality rate of about 40 % in children with laryngeal cysts was reported1. Vallecular cyst or pre-epiglottic cyst is a rare but recognized cause of respiratory distress in infancy or immediately after birth2. It has been associated with sudden airway obstruction resulting in death. Vallecular cyst consists of a unilocular cystic mass of variable size arising from the lingual surface of the epiglottis and containing clear, non-infected fluid3.
Synonyms : Vallecular cyst has been reported in the literature under different names and this has led to some confusion. Terms used have included mucous retention cyst, epiglottic cyst, base-of-the-tongue cyst, congenital cyst and more recently ductal cyst3. This later name originates from the classification of DeSanto et al, in which they grouped laryngeal cysts according to their location and surface mucosa (Thyroid cartilage foraminal cysts ; Saccular cysts ; Ductal cysts)3. This classification has become popular but has the limitation that, it was largely based on observation in adults and did not recognize different anatomical sites and variations in clinical presentation.
Case report : A 22-year-old-woman, gravida 2, para 1, had an anterior fetal neck cyst diagnosed on routine ultrasound survey at 25 weeks gestation during an consultation for uterine contraction. The family history of both parents was unremarkable.
The patient was referred to the regional perinatal referral centre at 28 weeks of gestation. Sonographic examination revealed a singleton vertex-presenting fetus with a hypoechoic cystic mass, behind and below the tongue (Figure 1).
The chest and facial structures appeared normal. An axial scan of the oropharyngeal region showed a cystic mass of 35 X 30 mm within the oral cavity, attached to the inferior aspect of the tongue (Figure 2).
Cystic component were noted. The tumour appeared to be intimately attached to the base of the tongue, but did not seem to involve all the pharyngeal region (Figure 3).
The margins were distinct and no echoes could be seen inside the mass. Color Doppler studies of the fetal neck mass showed no neovascularity, either inside or outside the cyst. While we were studying the buccal mass, movement of the fetal mouth was not impaired and the fetus swallows normally some amniotic fluid. This caused the mass to be pulled towards the retropharynx and demonstrated that the walls of the mass were soft and malleable. There was no dilatation of the hypopharynx. Nevertheless the presence of polyhydramnios and of a little filled stomach led us to conclude that the cystic mass was not obstructing totally the esophagus. The same conclusion could not be drawn for the trachea, however and so the possibility of upper airway obstruction had to be taken into account. Antenatal aspiration of the cyst was not attempted in utero. After discussions (about fetal risk) with the patient, we decided to perform serial ultrasound examinations at weekly intervals to follow the growth of the tumour.
Nevertheless at 28 week and three days, the amniotic fluid was on excess and there was important uterine activity. The patient was hospitalized. An amniocentesis was necessary (2.6 l). The genetic studies reported a normal female chromosome study (46, XX) and normal amniotic fluid acetylcholinesterase.
By 30 weeks, the mass has the same dimensions, but there was a further increased amniotic fluid and suggestions of obstruction of the hypopharynx. There was a significant uterine activity and maternal betamethasone therapy was begun at 32 weeks due to the high risk for premature delivery. A repeat amniocentesis was done to relieve the patient (2.4 l).
Magnetic resonance imaging (MRI) demonstrated the mass to be a 3 x 3 x 3 cm sublingual cystic lesion with no attachment to the hyoid bone and salivary glands (Figure 4 ; Figure 5).
A vallecular cyst was suggested.
At 33 weeks a conference including obstetricians, perinatologists, pediatrics otolaryngologists, and pediatric surgeons was convened and a cesarean section was programmed to relieve the patient. The otolaryngologist specialized in airway management, were to be ready with all the equipment necessary to perform immediate tracheostomy if the airway was compromised. Two neonatologists were present in the delivery room, to assist in resuscitation of the baby and provision of vascular access. The mass occupied the entire oral cavity without enlargement of the bony structures. The baby could not cry. So after birth by cesarean, the cyst was partly drained with a syringe and decompressing. The baby was orally intubated in less than three min from delivery. The airway was stable with intubation. The cord pH was 7,38. Birth weight was 1850 g. Nevertheless the baby received surfactant. Her lungs were very noncompliant and required high-pressure settings on the ventilator during 14 days. This was thought to be secondary to the mass preventing alveolar expansion in utero. When attempting to wean her off of mechanical ventilation, the airway would collapse. Postoperative complications arrived at days 6 with respiratory distress. A multicystic leukomalacia periventricular hemorrhage was noted at six weeks of life.
The aspirated fluid was sent for amylase, LDH and cell count. All of these studies were normal. The fluid contained ciliated epithelium. Surgical excision was performed on day ten of life (marsupialization), using nasotracheal intubation. The histologic diagnosis was a respiratory cyst. The baby was kept intubated for 30 days postoperatively and subsequently extubated with difficulties. The patient, oxygeno-dependant, was discharged from hospital after 38 days. Neurologic forecast is reserved.
History : Vallecular cyst is a rare but well-recognized cause of upper airway obstruction and death in newborns and infants. Due to the anatomical location of the cyst, an infant with vallecular cyst is at risk of sudden airway obstruction and death3.
Prevalence : Not precisely known, but authors agree that these perinatal cases are an extremely rare condition.
Etiology : Sporadic.
Pathogenesis : There are several theories for the pathogenesis of vallecular cyst. These lesions most likely result from obstruction of mucous gland at the base of the tongue. The vallecular cyst are lined with mucous glands and with continued mucous secretion, the lesion gradually increases in size. Other potential causes of cyst include embryological malformation (angiomatous, lymphatic malformation,…). vallecular cyst is considered to be more common in adults than children3. But vallecular cyst with respiratory epithelium are rare4.
When the embryo is approximately three weeks old, the primordium of the respiratory system appears as an endodermal outgrowth from the ventral wall of the foregut immediately caudal to the hypobranchial eminence. The ventrally placed respiratory primordium then becomes separated from the dorsal portion, the esophagus, except at the entrance to the larynx, where it maintains its communication with the foregut through the laryngeal orifice. The remaining part of the gut contributes to the development of the stomach and duodenum, just caudal to the liver5. Because of the proximity of the primitive gut and the pharyngeal arches, which contain the developing tongue, embryonal rests of the gut may become misplaced in the developing tongue. It is believed that these epithelial remnants may subsequently contribute to the development of cystic lesions of the tongue4-5-6. Constantinides et al have suggested that the presence of ciliated epithelium, which is the hallmark of the primitive foregut, warrants use of the term « intralingual cyst of foregut origin »5.
Associated anomalies : Associated anomalies are rare.
- Pulmonary hypoplasia.
- Trachea, cervical vessels and hypoglossal nerve compression.
Differential diagnosis : The differential diagnosis of lesions in the vallecular region includes epidermoid cyst, dermoid cyst, thyroglossal duct cyst, mucocele, enteric duplication cyst, lingual bronchogenic cyst, hemangioma, cystic hygroma, teratoma, hamartoma, lymphangioma and thyroid remnant cyst3-5.
- Hemangioma : The diagnosis of fetal neck hemangioma is made by ultrasonography as a translucent mass, in which pulsating Doppler flow signals is detected. MRI is recommended to plan perinatal treatment and particularly for obtaining precise information about tumor and adjacent organ7. Nevertheless this type of mesenchymal tumor has never been reported to involve the tongue in a fetus8.
- Lingual lymphangioma : The most common vascular malformation affecting the pediatric airway is the lymphatic or lymphatic-venous malformation. These lesions can be divided into three subtypes based on the size of the predominating lymphatic spaces (capillary, cavernous) and the most common type cystic hygroma9.This one is the most difficult differential diagnosis, due to similarity in size, gross characteristics and often location. The margins are usually less well defined and most of these tumors arise in the posterior triangle of the neck. Nevertheless ultrasound scanning mostly reports a thin-walled multicystic multiseptate hypoechogenic mass whose size varies from small collections of fluid to enormous cysts10.
- Thyroglossal duct cyst and brachial cleft cysts : have the similar echo-texture than lymphangioma, but are usually located below the mandible in the cervical region8-11.
- Cervical meningocele and anterior cephalocele : are easily eliminated, because of the anterior localization of the cysts observed on the sagittal view8-10.
- Congenital epulis : or congenital gingival granular cell tumour, is an uncommon benign intraoral tumour. Seven cases of antenatal detection on late second or third-trimester ultrasound have been reported12-13. The tumour may be single or multiple and is usually found on the maxillary alveolar ridge or the mandible12-13.
- Congenital ranula : or retention salivary, normally seen in children, results from a dilatation of the sublingual or submaxillary gland ducts in the floor of the mouth14. These pseudocysts are normally located in the sublingual space between the mylohyoid muscle and the lingual mucosa. They can be classified according to their localization12-14, simple ranulas (in the floor of the mouth), cervical ranulas (in the paracervical area) and plunging ranulas near the superior airway. They can extend into the floor of the mouth and the only way to differentiate them from other types is by histopathology. Ultrasonographically they are indistinguishable.
- Mucoceles: In the oral cavity, mucoceles refer to collections of mucus resulting from obstruction of, or leakage from a major or minor salivary gland15. Mucoceles occur commonly in the oral cavity, typically on the lower tip but also in unusual locations, such as in young patients16.
- Heterotopic gastrointestinal cyst : Intra-oral duplication cysts of the alimentary tract are rare. They tend to occur in the floor of the mouth or within the tongue16. In large series, only 1,8 % of alimentary tract duplications were noted to be in the cervical region. They are usually diagnosed in the newborn period but may be undetected for years if asymptomatic and small17. In fact the most difficult differential diagnosis is with heterotopic gastrointestinal cysts of the oral cavity, which involve the tongue and floor of the mouth in 97 %8. However prenatal diagnosis of such lesions has never been reported8. They tend to occur in the floor of the mouth or within the tongue16.
- Cervical-facial teratoma : About only 5 % of all teratoma occur in the face and neck region, with anterior and lateral neck region being most common18. When the teratoma arises from the sphenoid bone, the palate or the pharynx, it is called an epignathus, which appears as a complex solid-cystic tumor with mixed areas of hypo and hyper-echogenicity8. It found in association with polyhydramnios8-19. Protrusion through the mouth can distort the oro-facial anatomy and cause respiratory distress at birth20-21.
Sonographic findings : In the second trimester, ultrasonography in this area may be more informative because the fetal head is not yet in a flexed position and imaging of the head can usually be carried out from several directions22. There were no flow voids on either image or extensions of the mass into the surrounding soft tissue. The thyroid scan can be made and demonstrated no functioning thyroid tissue at the base of the tongue23. Transabdominal sagittal imaging, which would be particularly useful for examination of the nasopharynx, and laryngeal area, is often impossible by ultrasound in late pregnancy, because the fetal head is deeply engaged in a transverse position in the maternal pelvis. A karyotype study is not absolutely necessary.
Magnetic resonance imaging (MRI) : Even thought obstetric ultrasonography currently has a high-resolution capacity, acoustic shadowing disturbs visualization of structures that are surrounded by bony material22. Otherwise in late pregnancy in particular, in the region of the fetal pharynx, neck and posterior fossa, interpretation of ultrasonographic images is sometimes equivocal. Therefore MRI is a valuable additional imaging method both to diagnose and to exclude malformations and also to image the fetal anatomy adjacent to a malformation. Computed tomography and or MRI can be used to determine the extent of the cyst. The patient’s young age, the sharp margination of the lesion, the lack of surrounding tissues edema and a homogeneous T2 signal favors a benign diagnosis. Although greatly aided by imaging studies, visualization by direct laryngoscopy is still the major diagnosis tool in the diagnosis of vallecular cyst23.
Implications for targeted examinations :
In cases of polyhydramnios, pharynx and neck should be investigated thoroughly in order to identify lesions that could cause obstructions labor and neonatal ventilations problems. Prenatally it possible to define the anatomical relationship of cysts to the adjacent tissues and thus the planning of postnatal surgery became easier. Therefore, a chance to localize obstruction or verify the patency of the pharyngeal area prenatally by ultrasound or by MRI is important22. Nevertheless, three dimensional ultrasonography and harmonic ultrasound imaging may also provide better possibilities to visualize the anatomy of the fetal pharynx, neck.
Prognosis : Depends on the size of the tumor and the tracheal compression. Most infants can die immediately without perinatal management.
Recurrence risk : none
Management : The widespread use of prenatal ultrasound can lead to earlier diagnosis of vallecular cyst and allows for appropriate counseling and preparation at delivery and for the proper preparation of personal and equipment in the management of these neonates. Prenatal ultrasound can detect the presence of a fetal neck mass and allows the obstetrician to collaborate with the neonatologist, pediatric surgeon and pediatric otolaryngologist in order to plan for perinatal management. So that the explications are made for parents and the time and place of delivery can be addressed and planning for resuscitative efforts can be organized in advance. If the airway is quickly stabilized and resection of the tumor is not delayed, the prognosis is good. If the airway is compromised, aspiration of the cyst can be done to improve the access to the oropharynx for intubation. Preparation for emergent tracheostomy should be done before delivery in case oral intubation is not possible. Once extent of the lesion is identified, complete cyst excision is the treatment of choice. Indeed, aspiration of the cyst does not resolve the problem and recurrence is likely16.
During the birth, the placenta cord can be left undivided until the airway is secured. So perinatal management might require complicated procedures such as OOPS (Operation on placental support), in which the neonate undergoes surgery during an elective Cesarean section under tocolysis while its oxygen supply is still maintained through the placenta24.
Marsupialization, which is the treatment for the vallecular cyst, may be performed with a carbon dioxide laser or an electrocautery unit3-24. In the literature, there were no long-term recurrences in any of the patients.
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