SAMIR S.SHAHMD, MSCE
Magnetic resonance imaging of the head revealed a subtle nasal dermal sinus tract that extended from the cutaneous site to the nasal bone junction posteriorly, without enhancement, associated mass, or intracranial component (Figure 2). Congenital midline lesions on the nose are rare, occurring once in every 20 000 to 40 000 live births.1Nasal dermoid sinus cysts are a subset of congenital midline lesions of the nose; this inclusive term encompasses nasal dermoid cysts and nasal dermal sinuses.2,3Overall, nasal dermoid sinus cysts are the most common congenital midline nasal masses and account for 4% to 12% of dermoid cysts of the head and neck.1,4
A subtle nasal dermal sinus tract extending from the cutaneous site to the nasal bone junction posteriorly, without enhancement, associated mass, or intracranial component.
Nasal dermoid sinus cysts are usually firm, nonpulsatile, noncompressible nodules that do not transilluminate. Unlike encephaloceles, which also present as nasal midline masses, dermoid cysts do not expand with compression of the jugular vein (a negative result on the Furstenberg test).5They can occur anywhere from the glabella to the nasal tip and are sometimes associated with a sinus ostium or pit.3,5This pit may exhibit protruding hairs, a pathognomonic finding of nasal dermoid sinus cysts.6A sinus ostium, by definition, signifies the presence of an underlying sinus tract that may range in depth from a blind-ending pouch to a patent connection with the intracranial space. However, nasal dermoid cysts without visible sinus pits may still extend into the intracranial space.5
Nasal dermoid sinus cysts can have intracranial connections as well. During craniofacial development, a space is formed between the nasal bones and deeper cartilaginous structures known as the prenasal space. A small projection of dura extends through this space and connects to the overlying nasal skin. As the nasal process of the frontal bone grows together, the skin and dura normally separate. If this separation is incomplete, the receding dura may pull the nasal ectoderm inward to form a sinus, cyst, or both.1,7,8Most nasal dermoid sinus cysts are not associated with other anatomic abnormalities, though additional craniofacial defects such as craniosynostosis, cleft palate, and hemifacial microsomia have been observed.9
Though present at birth, nasal dermoid sinus cysts may be asymptomatic and thus remain undiagnosed for months or years, as in this patient. Common complications include recurrent cellulitis and abscesses. Meningitis or osteomyelitis of the nasal and frontal bones may result from extension of the dermoid sinus cyst into the intracranial space.3,5
The frequency of nasal dermal sinus cysts that maintain a connection with the intracranial space ranges from 5.6% to 45.5% in different case series.6,8Magnetic resonance imaging should be performed to identify intracranial connections and to evaluate the depth and extension of the nasal dermoid sinus cyst before surgical manipulation. Surgical excision of nasal dermoid sinus cysts, with careful tracking of the sinus tract portion, is recommended to prevent infection or potential distortion of the underlying nasal bone structure. Though treatment of these lesions by excision is generally successful and produces acceptable aesthetic outcomes, nasal dermoid sinus cysts may recur if incompletely removed.8
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Correspondence:Andrea L. Zaenglein, MD, Department of Dermatology HU14, the Pennsylvania State University/Milton S. Hershey Medical Center, 500 University Dr, Hershey, PA 17033 (email@example.com).
Accepted for Publication:January 14, 2010.
Author Contributions:Study concept and design: Horner and Zaenglein. Analysis and interpretation of data: Quach and Sabat. Drafting of the manuscript: Quach, Horner, and Sabat. Critical revision of the manuscript for important intellectual content: Horner and Zaenglein. Administrative, technical, and material support: Sabat. Study supervision: Horner and Zaenglein.
Financial Disclosure:None reported.
Picture of the Month—Diagnosis. Arch Pediatr Adolesc Med. 2010;164(8):770. doi:10.1001/archpediatrics.2010.131-b