With time, however, this cervical sinus eventually becomes narrowed to a small channel referred to as the cervical duct. This will eventually be obliterated. It is from failure of the cervical sinus to completely obliterate that there is the formation of branchial cysts, with the exception of first branchial cysts. If there is persistence of the cervical duct, a branchial fistula may exist, connecting the skin to the lumen of the foregut; whereas, a branchial sinus, which ends blindly, may from either persistent cervical duct or abnormal breakdown of a closing membrane. As development continues the branchial clefts and pouches are also obliterated with the exception of the first branchial cleft. Portions the first branchial cleft deepen to form the external auditory meatus.
Several structures are derived from the branchial clefts (ectoderm), the branchial arches (mesoderm), and the branchial pouches (endoderm). The first branchial pouch forms the eustachian tube, the tympanic cavity, the mastoid antrum and cells, and the tympanic membrane, while the second branchial pouch forms the palatine tonsils and supratonsillar fossa. From the third pouch comes the inferior parathyroid, the thymus, and the piriform fossa. Finally, the fourth branchial pouch produces the superior parathyroids.
The branchial arches, as previously mentioned, contain a cartilaginous skeleton, muscle primordia, a nerve and an artery. The first arch contributes the mandible, teeth, malleus and incus, while the second arch forms the body and lesser horns of the hyoid in addition to the stapes and styloid process. The third and fourth arch are the forerunners of the laryngeal skeleton. In regards to the arterial component of the arches, the external maxillary artery is formed from the first branchial arch; whereas, the second arch is responsible for the stapedial artery. The third arch forms the proximal portion of the internal carotid artery in addition to the external carotid and common carotid arteries. The arch of the aorta comes from the fourth arch artery as well as a portion of the proximal subclavian artery on the right. The sixth arch artery may persist as the ductus arteriosus on the left, but it forms the pulmonary artery on the right side.
The nerve of the first arch is the mandibular division of the trigeminal nerve. This then innervates the appropriate muscles also derived from the first arch: the muscles of mastication, the anterior belly of the diagastric, the mylohyoid, the tensor tympani, and the tensor veli palatini. From the second arch, one finds the facial nerve and its associated muscles -- the platysma, the posterior belly of the digastric, the stapedial muscle, and the muscles of facial expression. The eight cranial nerve is also derived from the second arch. From the third arch, the glossopharyngeal nerve is derived as well as the superior constrictor muscle; whereas, the vagus nerve comes from the fourth branchial arch innervating the laryngeal muscles which are also derived from this arch. Finally, the eleventh cranial nerve comes from the sixth arch.
Clinically, these may appear as parotid masses, parotitis, or ottorhea / otalgia if there is a tract with the external auditory canal. The treatment is surgical excision, depending on the degree of problems that this poses to the patient. Pre-operatively, it may be helpful to outline a sinus tract or fistula with a radiopaque dyes to confirm its course. Because of the close proximity of the cyst and tract to the parotid gland and facial nerve, a superficial parotidectomy and careful dissection of the facial nerve is often required. After the facial nerve is protected from damage, the cyst and tract may then be dissected free close to or at its termination with the external auditory canal. It may be necessary to excise a portion of the canal skin and cartilage and allowing the inferior portion of the canal to heal by secondary intention.
It should be noted that third and fourth branchial anomalies have reportedly been associated with recurrent acute suppurative thyroiditis of childhood. There is usually a polymicrobial infection with cultures growing Clostridium, E. Coli, Klebsiella, and Proteus requiring aggressive antibiotic therapy.
As it is intraluminal, it does not present as a neck mass. The external laryngocele is seen as a lateral swelling in the neck and passes superiorly through the opening of the thyrohyoid membrane from where the superior laryngeal nerve and vessels pass. Finally, the combined laryngocele has features of both internal and external. Clinically, presenting symptoms includes lateral neck mass, dysphagia, cough, dyspnea, and occasionally a gurgling sensation as the dilatation releases the contained air. On physical examination, the external and combined laryngoceles may appear as intralaryngeal pressures are elevated and is an easily compressible mass. Additionally, these may present as an acute cervical inflammation if the sac becomes secondarily infected, filled with a purulent fluid, forming a laryngopyocele. Besides the clinical picture, radiographic imaging such as a CT scan will confirm the diagnosis.
The management of symptomatic internal and external laryngoceles is surgical, usually through an external approach. Prior to excision of the laryngocele, it is important that a thorough endoscopic examination is performed to rule-out an underlying carcinoma that may be creating a check-valve within the ventricle. It has been found that there is an incidence of carcinoma in patients presenting with a laryngocele in 2% - 18%. For the external laryngocele, a horizontal incision is made at the level of the cystic mass at or below the level of the hyoid bone. Dissection is carried subplatysmally removing the overlying soft tissues until the cyst is encountered anterior to the carotid sheath. The cyst is then traced to the thyrohyoid membrane with careful identification of the superior laryngeal nerve. If there is no significant internal component the cyst may be ligated without entering the larynx.
For a combined laryngocele or large internal laryngocele, a lateral thyrotomy may be indicated for proper excision. After dividing or retracting the thryohyoid and sternothyroid muscles, the perichondrium on the thyroid cartilage is incised along the upper border and elevated inferiorly. The superior laryngeal nerve is identified and protected. After measuring the thyroid cartilage, a point is marked at an area just above the midportion and is connected to a point on the upper border of the thyroid cartilage, medial to the entrance of the superior laryngeal nerve. The limited lateral thyrotomy is then performed either with an oscillating saw or knife with care taken not to violate the laryngeal lumen. The internal laryngocele may then be identified and traced submucosally to its termination and then ligated. For small, isolated internal laryngoceles, several reports have shown success with laryngoscopic laser excision.
Teratomas are seen in 1:4000 births and have a proclivity for the gonadal, retroperitoneal, mediastinal, and sacrococcygeal regions. In the head and neck regions, however, these large, encapsulated semicystic masses may be uncommonly found in the nasopharynx, nose, orbit, oral cavity, or the neck. Maternal polyhydraminos is seen in 18% of the cases of cervical teratomas. For the teratomas in the neck, these are generally apparent at birth and may cause respiratory distress, depending on the size. It should be noted that cervical teratomas may be intimately associated with the thyroid gland and in addition to tracheal compression they may cause esophageal compression. Because of the impending airway compromise associated with these lesions, surgical excision is performed in an emergent fashion. While most teratomas are generally considered benign lesions, there is a 20% incidence of malignancy arising in these lesions, with considerable variation among primary sites, i.e. far more common in gonadal teratomas than cervical teratomas (rare). For malignant lesions, surgical excision followed by multiple drug chemotherapy or radiation therapy is required. Epignathi represents the last group and shows the highest degree of differentiation, showing developed fetal organs and limbs. These are typically not compatible with life.
Treatment is surgical excision. Local excision is not advocated because of the high recurrence rate. The surgical approach requires raising a short superiorly based flap slightly below the level of the hyoid bone, at the level of the cyst. Dissection is carried down to the cyst, allowing further dissection of the soft tissue off of the mass. This is then followed superiorly to the tongue base. Before dissecting into the tongue base, the center section of the hyoid bone is released by using bone cutting forceps. This will allow adequate retraction of the specimen as the cystic tract is followed to the foramen cecum where a cuff of the tongue base is taken with the specimen. It has been noted that excising the central portion of the hyoid bone along with a cuff of tongue base reduces the rate of recurrence drops to 3%.
For infants with lesions in the upper periorbital region, there may be significant visual obstruction that causes deprivation amblyopia, while distortion of the cornea may cause a refractive error causing astigmatic amblyopia. Regarding subglottic hemangiomas, the need for treatment is obvious. The child may present with biphasic stridor as the mass undergoes its proliferative phase or it may first appear as a protracted or recurrent laryngeotracheal bronchitis. Ulceration and bleeding may also occur as the hemangioma enlarges to penetrate the epidermal basement membrane. Depending on the complexity and extent of this morbidity, it may necessitate treatment. Of the more worrisome complications of hemangiomas is congestive heart failure. High-output heart failure may occur with large cervicofacial hemangiomas or in the patient with cutaneous plus visceral lesions, especially within the liver. In platelet trapping coagulopathy, also referred to as Kasabach-Merritt syndrome, it occurs early in the proliferative phase and clinically manifests as petechiae, ecchymosis and possibly more serious hemorrhagic events in the gastrointestinal, pulmonary, or central nervous systems. In this syndrome, the hematological profile will typically show a profound thrombocytopenia, low fibrinogen levels, and extremely prolonged prothrombin and thromboplastin times. Mortality has been to be as high as 30 - 40% in patients with platelet trapping coagulopathy despite treatment. For those lesions that require treatment, the options exist for pharmacological therapy, laser ablative, and surgical excision.
High dose corticosteroid treatment (2 to 3 mg/kg/day) has been shown to be effective in treating endangering hemangiomas, with a response rate ranging from 30 - 60%. Within hours to days of beginning treatment, a response should be noted; on the other hand, if no regression is noted after seven days of steroid use, the lesion is considered unresponsive. For the responsive lesions, steroid use is tapered to a lower level and is continued until the lesion will normally begin its involutional stage (at 10 to 12 months). Besides systemic corticosteroids, intralesional injections of triamcinolone acetate and betamethasone administered every 4 - 6 weeks may also prove to be an effective means of treatment. Interferon-alpha-2a has also been described in treating hemangiomas because of its antiangiogenic effects. The reports are somewhat preliminary at this time with promising results thus far, especially in patients exhibiting the Kasabach-Merritt syndrome. For infants with subglottic hemangiomas with evidence of respiratory distress, the carbon dioxide laser can ablate the lesion, especially in those infants not responding to systemic corticosteroids. Finally, surgical excision during childhood may be used to remove any resulting fibrofatty residual tissue or skin laxity after the lesion has involuted. Additionally, in certain cases where there are extreme psychosocial issues, especially in the child with a nasal or lip lesion, subtotal or staged excision with contouring may be indicated.
Capillary malformations contain numerous dilated capillaries or venule sized vessels typically located in the superficial dermis. It is important to note that those infants with a lesion involving the ophthalmic division of the trigeminal nerve may signal the patient has Sturge-Weber syndrome. In this syndrome, there is concomitant capillary, venous, and arteriovenous malformations of the leptomeninges which contributes to progressive atrophy and degeneration of the cerebral cortex. Laser therapy has been an effective treatment modality and is currently considered the treatment of choice. In adults, the argon laser produces thermal thrombosis of the lesion with later lightening and flattening of the skin. In contrast, the flashlamp pulsed tunable dye laser may be useful in younger children, in patients with lightly colored lesions, and in patients with extremely heat sensitive skin. In certain instances, surgical excision may be necessitated with reconstruction using locoregional flaps, skin grafting, or tissue expansion.
Venous malformations were referred to as cavernous hemangiomas or varicose hemangiomas. Histologically, these lesions are characterized by largely dilated or ectatic vascular channels with a normal endothelial lining with often associated areas of thrombosis. There may also be a component of capillary or lymphatic anomalies within the venous malformation. These lesions are commonly found on the lip or cheek area within the head and neck region, and are seen as a soft, compressible, nonpulsatile mass which refills rapidly after releasing. These lesions have also been described within skeletal muscle tissue, especially the masseter, as well as within the craniofacial skeleton (i.e. mandible). Radiographically, the intraosseous lesions demonstrate a pathognomonic "honeycombing" or "soap bubble'" appearance. Because these are low-flow lesions, they are prone to phlebothrombitis which may present as recurrent pain and tenderness in the involved areas. In the treatment of venous malformations, surgical resection, often subtotal, may be indicated for large or symptomatic lesions which results in bulk reduction and improved contouring; whereas, the injection of a sclerosing agent into the epicenter with the assistance of an interventional radiologists may be indicated in smaller, selected lesions. In sclerosing, the inflowing arterial system and outflowing venous system must be occluded.
Lymphatic malformations are characterized by multiple dilated lymphatic channels that may have components of capillary anomalies (capillary-lymphatic malformation) or venous anomalies (lymphatovenous malformation). Often there is a notable hemorrhage within the lymphatic spaces. There is a wide variety of these lesions, varying from the cystic type (referred to as cystic hygroma) which occurs predominately in the posterior triangle of the neck and shows less infiltration into the surrounding tissues, to a more severe type which shows extensive infiltration into the surrounding tissues. Some lymphatic malformations may also be associated with obvious bone and soft tissue hypertrophy. A more formal classification of lymphatic malformations has been described. Type I are seen as lesions below the mylohyoid muscle and are usually seen in the anterior and posterior triangles. These lesions are will circumscribed, largely cystic, and discreet without evidence of infiltration into the surrounding structures, as previously noted for cystic hygromas.
In contrast, type II malformations are seen above the mylohyoid muscle and are seen primarily in the oral cavity, lip, and tongue. These lesions are less discreet, with evidence of obscured planes secondary to infiltration into the nearby tissues. Treatment is based on surgical excision, with the degree of success far greater with the type I lesions than that of type II. For the type I lesions, complete resection is usually possible and may be performed within the first 9 - 12 months of age. In contrast, the type II lesions are approached with reasonable expectations, of ten requiring multiple procedures and highly unlikely total resection. In cases where the lesion is not amenable to safe dissection, i.e. the supraglottis, the CO2 laser has been useful for resection.
High-flow vascular anomalies of the head and neck are characterized by arteriovenous malformations. The is microscopic evidence of multiple arteriovenous shunts with thick walled, irregular caliber arterial vessels with concomitant venous changes consisting of hypertrophy, intimal thickening, and sclerosis secondary to the high flow associated with the shunting. Clinically, these lesions are erythematous, staining lesions of the skin with an associated thrill to palpation and bruit to auscultation. These lesions, as most vascular malformations, may change suddenly in response to minimal trauma, infection, or hormonal changes. Clinically, these lesions may cause problems with skin necrosis and craniofacial destruction secondary to shunting of the blood from these structures as well as from compressive or erosive effects. Because of these high- flowing lesions, heart failure may be a coincident morbidity. For the symptomatic lesion, pre- operative evaluation of the lesion with MRI should be undertaken along with angiography which allows superselective embolization of the lesion, if so indicated. Long term success, however, requires total resection of the involved tissue with often complex reconstruction, i.e. microvascular tissue transfer.
In evaluating these lesions, the CT scan is invaluable with the fluoroscopic or even plain film also assisting in the diagnosis and management plan. The literature indicates that endoscopic and barium swallow studies have limitations in the diagnosis and preoperative planning of the esophageal duplication cyst. Endoscopically, a submucosal mass with normal overlying mucosa is typically found, making it difficult to distinguish from other lesions, such as a leiomyoma. This is similar for the barium swallow. While technically difficult, endosonography has been used to assist in the diagnosis. For the rare lesion that communicates with the spinal canal, myelography is typically performed. Treatment is surgical excision. Depending on the location of the cyst, the approach may require a cervical, thoracotomy or laparotomy for appropriate removal. For the neurenteric communication, these must be carefully dissected and closed.
Because hemangiomas do tend to involute, conservative management must be recommended unless there is functional impairment with vision, airway, swallowing, or nerve function. In these cases steroid use may be appropriate but consideration of steroid drawbacks should be made including hypertension, intracranial pressure, and chickenpox exposure. Congenital lymphatic malformations do not tend involute and should be excised without sacrifice of vital structures when the child is old enough to undergo the surgery and preferably before re-infection makes the surgery more difficult.
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