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DOI: 10.1055/s-0036-1584525
Nasal Dermal Sinus Associated with a Dumbbell-Shaped Dermoid: A Case Report
Address for correspondence
Publication History
12 January 2016
15 April 2016
Publication Date:
20 June 2016 (online)
Abstract
Nasal dermal sinus is a rare congenital anomaly. We report a case of the dermal sinus associated with a dumbbell-shaped dermoid and demonstrate the detailed anatomy. The patient was a boy aged 1 year and 4 months with a small pit at his nasion from birth and developed swelling of the forehead. The sagittal view of a T2-weighted image demonstrated a dumbbell-shaped, mixed intense dermoid at the foramen cecum. The sinus tract was depicted as a strand of isointensity between the dermoid and the nasion. Serial sagittal views of T1-weighted images revealed the capsule of the dermoid enhanced with contrast medium, and that the subcutaneous abscess was in continuity with the dermoid. On diffusion-weighted imaging, both the dermoid and subcutaneous abscess were demonstrated as a hyperintensity. Serial sections of the sagittal and coronal computed tomography scans clearly showed an enlarged fonticulus frontalis and foramen cecum remnant and dehiscence of the crista galli. The purulent dermoid cyst including the capsule and the dermal sinus tract were removed completely. We describe our detailed anatomical relationship between the sinus tract with dumbbell-shaped dermoid and the surrounding structures, and emphasize the importance of these anatomy for operation.
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Introduction
Nasal dermal sinus is a very rare congenital anomaly that is frequently associated with inclusion cysts (dermoid or epidermoid).[1] [2] [3] At the end of the second month of gestation, the nasal and frontal bones are separated by the fonticulus frontalis. In this period, the dura projects into the nasal area through the anterior skull base opening (foramen cecum), and lies in contact with the skin at the tip of the nose. Failure during ossification to obliterate this transcranial connection is the embryological pathway to nasal dermal sinus tract development.[1] [2] [3] [4] In the present case, combined use of high resolution magnetic resonance imaging and computed tomography (CT) clearly demonstrated the detailed anatomical relationship of the dermal sinus associated with a dumbbell-shaped dermoid to the surrounding structures such as the fonticulus frontalis and foramen cecum.[3] [5]
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Case Report
History and Examination
The patient was a boy aged 1 year and 4 months who had had a small pit at his nasion from birth and had developed swelling of the forehead. The pit seemed to be closed and no purulent discharge was noted ([Fig. 1A]). The sagittal view of a T2-weighted image demonstrated a dumbbell-shaped, mixed intense dermoid at the foramen cecum. The sinus tract was depicted as a strand of isointensity between the dermoid and the nasion. A subcutaneous abscess was noted adjacent to the dermoid, and the subcutaneous swelling of the forehead was demonstrated as hyperintensity ([Fig. 1B]). Serial sagittal views of T1-weighted images (T1WI) revealed the capsule of the dermoid enhanced with contrast medium (gadolinium-diethylenetriamine penta-acetic acid [Gd-DTPA]), and that the subcutaneous abscess was in continuity with the dermoid cyst. The sinus tract was not apparent on the T1WI ([Fig. 1C]). On axial view of the Gd-enhanced T1WI, the subcutaneous abscess was also noted adjacent to the dumbbell-shaped dermoid ([Fig. 1D]). On diffusion-weighted imaging, both the dermoid and subcutaneous abscess were demonstrated as a hyperintensity ([Fig. 1E]). Serial sections of the sagittal and coronal CT scans clearly showed an enlarged fonticulus frontalis and foramen cecum remnant and dehiscence of the crista galli ([Fig. 1F, G, H]). Three-dimensional CT imaging showed a bony defect at the midline of the junction of the frontal bone and the anterior fossa, with a bifid and bulging crista galli ([Fig. 1I]).
![](https://www.thieme-connect.de/media/jnlsr/201602/thumbnails/10-1055-s-0036-1584525-i160002-1.jpg)
![Zoom Image](/products/assets/desktop/css/img/icon-figure-zoom.png)
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Operation and Pathological Findings
The subcutaneous abscess was evacuated through a coronal skin incision on the frontal region, and then the purulent dermoid cyst including the capsule was removed. The part of the dermoid capsule that was tightly adherent to the dura was carefully coagulated. There was a bony defect at the nasion ([Fig. 2A]). The dermal sinus tract was also dissected through a tiny skin incision ([Fig. 2B]).
![](https://www.thieme-connect.de/media/jnlsr/201602/thumbnails/10-1055-s-0036-1584525-i160002-2.jpg)
![Zoom Image](/products/assets/desktop/css/img/icon-figure-zoom.png)
Microscopically, the dermoid cyst wall was typically lined by a keratinizing squamous epithelium. Intraluminal keratin and hair shafts were also demonstrated ([Fig. 2C]). The sinus tract was a ductal structure lined by stratified squamous epithelium ([Fig. 2D]). The orifice of the sinus was opened.
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Discussion
The schematic drawing in [Fig. 1J] demonstrates the detailed anatomical relationship between the sinus tract with dumbbell-shaped dermoid and the surrounding structures. The body of the dumbbell-shaped dermoid was located in the enlarged fonticulus frontalis and foramen cecum remnant; the head of the dumbbell was the intracranial extension of the dermoid with bulging dura. A bifid and bulging crista galli was also attributed to the intracranial extension of the dermoid. Although bacteriologic examination failed to reveal the causative agents, the microscopically opened sinus tract resulted in the formation of the subcutaneous abscess adjacent to the purulent dermoid.
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References
- 1 Barkovich AJ, Vandermarck P, Edwards MS, Cogen PH. Congenital nasal masses: CT and MR imaging features in 16 cases. AJNR Am J Neuroradiol 1991; 12 (1) 105-116
- 2 Hedlund G. Congenital frontonasal masses: developmental anatomy, malformations, and MR imaging. Pediatr Radiol 2006; 36 (7) 647-662 , quiz 726–727
- 3 Huisman TA, Schneider JF, Kellenberger CJ, Martin-Fiori E, Willi UV, Holzmann D. Developmental nasal midline masses in children: neuroradiological evaluation. Eur Radiol 2004; 14 (2) 243-249
- 4 Pratt LW. Midline cysts of the nasal dorsum: embryologic origin and treatment. Laryngoscope 1965; 75: 968-980
- 5 Post G, McMains KC, Kountakis SE. Adult nasal dermoid sinus cyst. Am J Otolaryngol 2005; 26 (6) 403-405
Address for correspondence
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References
- 1 Barkovich AJ, Vandermarck P, Edwards MS, Cogen PH. Congenital nasal masses: CT and MR imaging features in 16 cases. AJNR Am J Neuroradiol 1991; 12 (1) 105-116
- 2 Hedlund G. Congenital frontonasal masses: developmental anatomy, malformations, and MR imaging. Pediatr Radiol 2006; 36 (7) 647-662 , quiz 726–727
- 3 Huisman TA, Schneider JF, Kellenberger CJ, Martin-Fiori E, Willi UV, Holzmann D. Developmental nasal midline masses in children: neuroradiological evaluation. Eur Radiol 2004; 14 (2) 243-249
- 4 Pratt LW. Midline cysts of the nasal dorsum: embryologic origin and treatment. Laryngoscope 1965; 75: 968-980
- 5 Post G, McMains KC, Kountakis SE. Adult nasal dermoid sinus cyst. Am J Otolaryngol 2005; 26 (6) 403-405
![](https://www.thieme-connect.de/media/jnlsr/201602/thumbnails/10-1055-s-0036-1584525-i160002-1.jpg)
![Zoom Image](/products/assets/desktop/css/img/icon-figure-zoom.png)
![](https://www.thieme-connect.de/media/jnlsr/201602/thumbnails/10-1055-s-0036-1584525-i160002-2.jpg)
![Zoom Image](/products/assets/desktop/css/img/icon-figure-zoom.png)