Medical Journal of Dr. D.Y. Patil Vidyapeeth

CASE REPORT
Year
: 2012  |  Volume : 5  |  Issue : 1  |  Page : 47--50

Nasal dermoid cyst with intracranial extension and an atretic dermal sinus tract


Vikram Singh, Sanjeev Sehrawat, Amit Kharat, Rajesh Kuber 
 Department of Radio-Diagnosis, Padmashree Dr. D. Y. Patil Medical College, Sant Tukaram Nagar, Pune, Maharashtra, India

Correspondence Address:
Vikram Singh
Flat # 205, Building E, Kohinoor Vayona Apartments, Near Ginger Hotel, Pimpri - 400 018, Maharashtra
India

Abstract

Nasofrontal masses belong to the group of congenital midface anomalies (CMFA) in paediatric age group. Nasofrontal dermoids with patent dermal sinus tract is a rare anomaly resulting from the failure of normal embryogenic process. Most patients present in infancy or early childhood. CT and MRI together are usually required for definitive diagnosis. CT imaging provides vital information about the osseous involvement while MRI is crucial for evaluation of the intracranial extent and detailed tissue characterization. Knowledge of embryonic development is important in understanding the pathologies of nasofrontal masses in paediatric age group.



How to cite this article:
Singh V, Sehrawat S, Kharat A, Kuber R. Nasal dermoid cyst with intracranial extension and an atretic dermal sinus tract.Med J DY Patil Univ 2012;5:47-50


How to cite this URL:
Singh V, Sehrawat S, Kharat A, Kuber R. Nasal dermoid cyst with intracranial extension and an atretic dermal sinus tract. Med J DY Patil Univ [serial online] 2012 [cited 2021 Sep 21 ];5:47-50
Available from: https://www.mjdrdypu.org/text.asp?2012/5/1/47/97512


Full Text

 Introduction



Midline nasofrontal masses in paediatric age group belong to the group of rare congenital anomalies. Various classifications have been formulated to understand their development and progression. The usual list of differential diagnosis for such masses can be narrowed to nasal dermoid, epidermoid, nasal encephalocele and nasal gliomas. [1] Such masses also create concern in parents of the child regarding facial aesthetics. These conditions can be readily diagnosed using Computed Tomography and Magnetic Resonance Imaging, both being exquisitely non-invasive and complimentary.

 Case Report



Nine year old female child presented with gradually increasing swelling over the nasal bridge in midline since birth with thick cheesy (sebaceous) discharge on compression of nasal tip. On clinical examination it revealed a soft, painless and mobile swelling with a small opening on the tip of the nose [Figure 1]. No overlying skin discolouration or induration was seen. The child had normal birth from a nonconsanguineous marriage and normal developmental history. No other craniofacial abnormality was seen.{Figure 1}

The child was subjected to various investigations for evaluation. Radiograph of skull, lateral magnified view [Figure 2] revealed soft tissue swelling on the nasal region. No calcification was seen.{Figure 2}

In order to rule out vascular malformation, the patient was advised to go for a high resolution ultrasound using linear transducer (11 Mhz). Ultrasound examination revealed a well defined hypoechoic lesion [Figure 3]a and on colour doppler revealed mild peripheral vascularity at the nasal bridge [Figure 3]b.

Non contrast computed tomography revealed a hypodense lesion of CT values -8 to +10 HU with peripheral rim of calcification. It measured approximately 2 cm × 2 cm in size. No perilesional edema was seen [Figure 4]a and b.{Figure 3}{Figure 4}

Plain and contrast enhanced MRI scan of the brain and paranasal sinuses was performed using standard brain protocol with fat saturation sequences on a 1.5 T MRI scanner. The findings revealed a fairly well defined extraaxial midline lesion in the frontal region causing buckling of the adjacent cortex. It was hypointense on T1WI and FLAIR and hyperintense with surrounding (peripheral) hypointensity on T2WI [Figure 5]a-c. Coronal T2WI image reveals the inferior extent of the lesion appearing bright with surrounding hypointensity [Figure 6] Diffusion weighted image shows bright signal intensity of the lesion and low intensity signals on ADC map [Figure 7]a and b.{Figure 5}{Figure 6}{Figure 7}

Contrast enhanced images revealed mild rim like peripheral enhancement [Figure 8].{Figure 8}

The nasal bridge mass revealed isointense signals to grey matter on T1WI and FLAIR and hyperintense signals on T2WI. [[Figure 9] -Sagittal image]{Figure 9}

No connection was seen between the lesion on the nasal bridge and frontal lesion.

The imaging results suggested possibility of dermoid due to its characteristic appearance which was confirmed by histopathology [Figure 10].{Figure 10}

 Discussion



Congenital midface anomalies (CMFA) in children are uncommon. CMFA are the result of faulty regression of the embryologic dural diverticulum from the prenasal space and occur in one of every 20,000-40,000 births. The mass may be intranasal, extranasal, or a combination of the two. Intranasal masses are due to extension of dura mater through the foramen cecum into the prenasal space and nasal cavity. Congenital midline masses are often obvious at birth but can manifest at any age. [2] Midface disfigurement, nasal destruction, meningitis, and airway obstruction may occur.

Midline nasofrontal anomalies can be narrowed down to three major entities like nasal dermoid or epidermoids, nasal encephalocele and nasal gliomas. [1] The differentiation and characterization of these lesions require a thorough understanding of the features of these entities. It is therefore essential to understand the normal embryological course and development in order to reach a definitive diagnosis. An important feature of a midline nasal mass is their possible intracranial extension. The development of these masses with their extension intracranially is a result of delayed closure or patent anterior neuropore. A temporary gap forms at the junction of nasal and frontal bones called fonticulus nasofrontalis. [Figure 11]a-c Imaging helps characterize these lesions so that the surgical approach can be planned as extracranial, intracranial, or both. Findings that suggest intracranial extension include widening of the foramen cecum and a bifid or dystrophic crista galli. [4] {Figure 11}

A second possibility of abnormal development, the dural diverticulum may also become adherent to the ectoderm and pull ectodermal cells below the skin surface as it attempts to regress. If this happens, dermal sinus tracts form along the regression path of the dural diverticulum. Dermoid and epidermoid cysts can form either alone or with a dermal sinus tract along the path of regression. Both lesions may be indistinguishable on imaging, but dermoid cysts are more common along the glabella-nasion, and epidermoids are more common in the paramidline and the columella nasi (soft-tissue external end of the nasal septum). [5] Most of the dermoid and epidermoid cysts are of fluid density on CT and MRI, but dermoid cysts can sometimes have the imaging properties of fat in the nasofrontal region.

Dermoid and epidermoid cysts occur when skin elements are pulled into the prenasal space along with the regressing dural diverticulum. A sinus tract or mass, each of which is seen in 50% of the cases, may form anywhere along the course of the diverticulum from the columella to the anterior cranial fossa. [2],[6] In about 57% of affected patients an intracranial extension may be seen. [7] Dermoid cysts contain ectoderm with skin appendages, are slightly more common than epidermoid cysts, and are usually midline with a tendency to occur at the glabella. Epidermoid cysts are typically paramidline and may contain ectodermal elements without skin appendages, are usually tend to occur near the columella. [6],[7],[8] In approximately 84% of the cases dermoid or epidermoid cysts and dermal sinus tracts may present with a sinus tract opening, dimple, or tuft of hair present on the skin surface. [3]

 Conclusion



Evaluation of midline nasofrontal masses in pediatric age group requires a careful diagnostic approach. The tendency of these masses to extend intracranially also needs to be excluded in all cases; therefore all patients must undergo a detailed evaluation to exclude their intracranial extension. CT and MRI have proved to be useful in evaluation of nasofrontal masses. While CT can provide important information about the osseous involvement and MRI is useful in evaluating intracranial extension and tissue characterization. Imaging therefore plays an important role as it helps the surgeons to plan for appropriate surgical management.

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