Nasal Dermoid Sinus
A full-term infant was born via uncomplicated vaginal delivery to first-time parents. The pregnancy was unremarkable with normal ultrasonography and laboratory test findings, including a sequential integrated screen. The mother took prenatal vitamins during the pregnancy, and there was no family history of neural tube defects.
At birth, the infant was noted to have a pit midline between the eyes on the nasal root (Figure). A small, firm mass was palpated underneath the pit. No discharge was noted from the lesion, and there was no family history of similar lesions. The mass did not vary in size over the course of the hospital stay. At the birth hospital, ultrasonography was performed, and results showed a small focus of hypervascularity medial to the left orbit. The brain was normal in appearance, but the findings were not well characterized.
The infant was discharged home with a referral to pediatric neurosurgery for consultation and further imaging. At 1 month of age, the patient was evaluated by the craniofacial team, who felt that the findings of the physical examination were most consistent with a dermal sinus tract with an underlying dermoid cyst. Computed tomography (CT) was ordered to evaluate the skull, and magnetic resonance imaging (MRI) was ordered to evaluate for an intracranial extension of the dermoid. The results of both studies were inconclusive about bony extension, but no intracranial mass was seen. Surgery was performed at 1 year of age, and no bony extension was found. The results of the pathologic examination were consistent with a dermoid sinus tract. The patient has done well since the excision and has a minor scar at the surgical site.
Discussion
Congenital midline nasal lesions develop from abnormal closure of the anterior end of the neural tube. During development, a diverticulum extends from the dura through the foramen cecum of the skull to the skin of the nasal bridge. This diverticulum typically regresses completely. However, if the diverticulum pulls in skin structures during regression, a dermoid or epidermoid develops.
An epidermoid contains superficial skin, whereas a dermoid contains deeper skin structures such as sweat glands and hair follicles. Half of children with a dermoid have a pit,1 which most commonly presents at the osteocartilaginous junction of the nose but can occur anywhere from the glabella to the columella.1 A nasal dermoid can present as a cyst, sinus tract, or fistula into the intracranial space. If a fistula is present, it can predispose a child to meningitis.
Other congenital midline nasal lesions are gliomas and encephaloceles. A congenital nasal glioma is non-neoplastic heterotopic glial tissue, which is different than the various types of neoplastic gliomas. Fifteen percent of congenital nasal gliomas are connected by a fibrous stalk to the brain.1 They are covered by skin, are usually firm in appearance, and may have a red or bluish color. They do not fluctuate in size.
An encephalocele is a sac-like protrusion of the brain and the membranes that cover it through an opening in the skull. It is a type of neural tube defect. An encephalocele can vary in size based on intracranial pressure, and it may tend to enlarge with crying. An encephalocele is covered with skin but is soft and will transilluminate.
Gliomas occur randomly, while neural tube defects can be familial. To decrease the risk of neural tube defects, it is recommended that all women of childbearing age take a daily folic acid supplement (400-800 µg). A higher dose (4 mg) is recommended if there is a history of a prior child with a neural tube defect.2 Gliomas can be mistaken for hemangiomas.3 Both gliomas and encephaloceles have been observed in utero on fetal ultrasonography.4,5
Differentiation of these lesions can usually be made by physical examination based on the differences described above. Imaging must be performed to determine whether intracranial extension exists. CT is better at looking for bony defects, but MRI can better determine the presence of intracranial tissue. Patients should be referred to neurosurgery for surgical correction.
Michelle Leff, MD, FAAP, is a newborn hospitalist and an associate professor of pediatrics at the University of California in San Diego.
References
1. Hedlund G. Congenital frontonasal masses: developmental anatomy, malformations, and MR imaging. Pediatr Radiol. 2006;36(7):647-662.
2. U.S. Preventive Services Task Force. Folic acid to prevent neural tube defects: preventive medication. https://www.uspreventiveservicestaskforce.org/Page/Document/RecommendationStatementFinal/folic-acid-to-prevent-neural-tube-defects-preventive-medication. Published May 2009. Accessed November 7, 2016.
3. Dasgupta NR, Bentz ML. Nasal gliomas: identification and differentiation from hemangiomas. J Craniofac Surg. 2003;14(5):736-738.
4. Grzegorczyk V, Brasseur-Daudruy M, Labadie G, Cellier C, Verspyck E. Prenatal diagnosis of a nasal glioma. Pediatr Radiol. 2010;40(10):1706-1709.
5. Sing-Ling L, Tsai P, Cheng Y, Chang C, Ko H, Chang F. Prenatal diagnosis of fetal encephalocele using three-dimensional ultrasound. J Med Ultrasound. 2012;20(3):150-154.