Defects of embryologic development give rise to a variety of congenital lesions arising from the epithelium and are among the most common congenital lesions of the head and neck in the pediatric population. This article presents several congenital lesions of epithelial origin, including congenital midline cervical cleft, pilomatrixoma, dermoid, foregut duplication cysts, and preauricular sinuses and pits. In addition, the management of these lesions is reviewed.
Key points
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Congenital lesions of the epithelium have varied presentations, including clefts, cysts, sinuses and pits, and masses.
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Management ranges from simple observation for asymptomatic lesions to surgical excision with complex repair.
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Nasal dermoids may take a multidisciplinary approach with neurosurgical involvement for intracranial extension.
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Syndromes associated with these lesions must also be considered in the evaluation of the pediatric patient with these defects.
Introduction
Most masses of the head and neck in children are benign in nature. Most commonly, these lesions are congenital, inflammatory, or infectious in cause. Defects of epithelial origin are the result of failure of fusion during embryologic development, failure of involution of primordial remnants during embryologic development, and defects of ectodermal development during childhood.
Introduction
Most masses of the head and neck in children are benign in nature. Most commonly, these lesions are congenital, inflammatory, or infectious in cause. Defects of epithelial origin are the result of failure of fusion during embryologic development, failure of involution of primordial remnants during embryologic development, and defects of ectodermal development during childhood.
Congenital midline cervical cleft
Epidemiology
Congenital midline cervical cleft (CMCC) is a rare developmental defect of the anterior neck with fewer than 100 cases reported in the literature. These defects account for less than 2% of congenital cervical malformations. There is some predilection for caucasian female children, and it can occur as a concomitant lesion with thyroglossal duct cysts and branchial cleft anomalies with an incidence of 1.7% in this population. No familial inheritance pattern has been identified, and they are thought to be a sporadic defect.
Cause/Embryology
Although the exact cause of CMCC is unknown, it is generally thought to be the result of failure of midline fusion of the branchial arches. In normal embryologic development, during the third and fourth week of gestation, mesenchymal tissue migrates between the branchial arches, pushing the ectoderm outward and resulting in fusion of the arches. A disruption in this process results in a midline defect. Failure of fusion of the second (hyoid) arches results in CMCC, whereas defects of the first (mandibular) arches result in clefts of the lower lip, tongue, and mandible, as well as CMCC.
Presentation
CMCCs are present at birth, although they become more apparent over time. They may be overlooked or misdiagnosed early on. These lesions may present at any point in the anterior midline neck from the mandible to the sternum. There are 3 primary anatomic components in these lesions: a superior skin tag, a midline cleft of moist atrophic epidermis lacking adnexal structures, and a caudal sinus or duct at the inferior aspect of the cleft, which may drain mucous. The senior author has operated on many of these lesions, and in his experience, the skin tag associated with this lesion may present at the superior or inferior aspect of the defect. It is also noted that CMCCs are associated with a subcutaneous amorphous fibrous cord that traverses the sternum to the midline of the mandible. This cord as well as a paucity of dermis contributes to a contracture that results in a wry neck. In the senior author’s experience, there is nearly always a subcutaneous cord along the tract of the cleft, which may extend as high as the mandible and as low as the sternum. This cord is the result of maldevelopment of the median raphe of the strap muscles. CMCC may be a solitary deformity or may be accompanied by other lesions, such as thyroglossal duct cyst, branchial cleft cyst, ectopic bronchogenic cyst, cleft lip, mandible, or tongue, absence of hyoid bone or thyroid cartilage, cleft sternum, or congenital heart disease.
With time, the cleft heals with a scar, resulting in a web. The web may ultimately result in neck contracture, limited mobility, and functional impairment, or torticollis. In more severe cases, this webbing can result in micrognathia, or a bony spur of the mandible or sternum ( Fig. 1 ).
Diagnosis
The diagnosis is typically made by clinical presentation. Early in life CMCC will present with a midline cleft associated with a cord, and possibly a skin tag and a caudal sinus or duct. Over time, webbing or contracture may also be evident. Imaging is generally not necessary in the management of these lesions; however, the authors advocate ultrasound to rule out synchronous thyroglossal duct cyst or branchial cleft anomaly.
These lesions may be associated with other midline defects. Therefore, it is also important to inquire about signs of congenital heart disease. It is important to examine the sternum, mandible, and tongue for signs of cleft as well.
Management
Surgical excision is the treatment for CMCC. The entire tract, as well as the superior skin tag and the inferior sinus, must be excised to avoid drainage and recurrence of contracture. It is also necessary to dissect and excise the subcutaneous fibrous cord. The most frequently used technique for repair is multiple Z-plasties designed for lengthening of scar and release of contracture. A single Z-plasty can be used as well ( Figs. 2–4 ). The senior author has noted that small lesions less than 2 cm in size with lax adjacent skin can be excised and repaired primarily, without Z-plasty. These small lesions still require resection of the fibrous cord, and they represent a minority of cases.
The age of repair should be early, during infancy, to avoid contracture and cosmetic deformity.
Pilomatroxima
Epidemiology
Pilomatrixoma is a benign neoplasm of the dermis, occurring most frequently in children and young adults. It is reported that 40% occur before the age of 10 years and 60% occur before the age of 20 years. However, there is a second smaller peak of onset in the elderly. There is a female preponderance of these lesions as well.
Although extremely rare, malignant degeneration (pilomatrix carcinoma) of these lesions may also occur. There are fewer than 80 reported cases. Pilomatrix carcinoma is most common in the head and neck, with a male predominance and predominance among the elderly.
Cause
Pilomatrixoma is a benign tumor of ectodermal origin. They arise from matrix cells of the outer root sheath of the hair follicle. These lesions represent a disturbance of the hair follicle cycle in which development into mature hair fails to take place. The vast majority of cases are solitary, sporadic neoplasms. However, the lesion may also be associated with Gardner syndrome, myotonic muscular dystrophy (Steinert disease), sarcoidosis, skull dysostosis, Rubinstein-Taybi syndrome, and Turner syndrome.
Presentation
These lesions generally present in the first 2 decades of life as a gradually enlarging, painless, mobile subcutaneous mass. They often have a hard nodular surface, and overlying skin may demonstrate a bluish discoloration. These lesions may also demonstrate a “tent sign,” whereby stretching the skin over the surface of the lesion allows the nodular surface to become more apparent. Calcifications may be seen as yellow or white flecks seen through the skin surface. These lesions generally slide freely over the underlying tissues.
Pilomatrixoma most frequently presents in the head and neck. The most common sites of presentation are reported to be the neck, cheek, and periorbital skin, followed by the scalp ( Figs. 5 and 6 ). Two percent to 10% of cases will have multiple lesions.
Histology
Histopathologic examination of pilomatroxima demonstrates a well-circumscribed intradermal nodule with a capsule of compressed fibrous tissue.
There are distinct peripheral and central components of the tumor. The peripheral zone consists of small, uniform, darkly staining basaloid cells originating from the hair matrix cells, whereas the central portion is composed of remnants of cells that have lost their nuclei called “ghost cells” or “shadow cells.” These “ghost cells” are thought to be the product of apoptosis.
Calcification or ossification is also common and can be seen in 69% to 89% of cases.
Management
Imaging is generally not necessary in the workup of these superficial, benign lesions. However, pilomatrixoma in the parotid or preauricular region may warrant imaging, particularly if parotid dissection is anticipated.
Complete surgical excision is curative for these lesions ( Figs. 7–9 ). No additional therapy is needed if the lesion is removed in its entirety. Recurrence can occur, requiring additional surgery if excision is incomplete.
