NASAL DERMOIDS WITHOUT INTRACRANIAL EXTENSION IN TEENAGERS

INTRODUCTION

Congenital nasal deformities are rare, occurring in 1 in 20,000 to 40,000 newborns (1). These lesions include nasal cysts, fistulas, tumors and pits that have their origin in the ectodermal or neuroectodermal layers. An incorrect embryologic development of the nose in a phase of the nasal and anterior rhinobase separation constitutes the nasal anomaly.

The neuroectodermal anomalies include gliomas, meningoceles and meningoencefaloceles, and the ectodermal forms represent dermoid cysts with or without fistulas and dermoid nasal sinus cysts. The nasal dermoid cyst is a cystic formation occurring in the middle of the face and is commonly related to the nasal dorsum, glabella or medial canthus, usually without intracranial propagation. The dermoid nasal sinus cyst is a cystic mass spreading under the nasal dorsum to the foramen caecum with possible intracranial and extradural extension (2). Both should be differentiated from encephaleceles in this region.

There are two theories to interpret the pathogenesis of congenital ectodermal defects in the region of the nose and the anterior rhinobase. The cranial theory points to a prenasal space and differentiation of the rhinobase, where the remaining contact of the nasal skin and dura create a cystic tract with a dural attachment. The superficial theory, in contrast, identifies a failure of the ectodermal extension, with the ectodermal sticking between the two medial nasal processes, which leads to the creation of a sinus or a cyst (3).

Nasal dermoids manifest themselves with nasal swelling and usually contain skin adnexa (e.g. hair follicles or sebaceous glands). The clinical examination of patients with nasal fistula reveals a punctiform skin defect on the nasal dorsum with intermittent detritus discharge. In addition, nasal dermoid cysts often present with inflammation.

Variable deformation of the external nose such as nasal swelling, elevated nasal dorsal projection, nasal gibbus or nasal fistula are found after birth, or spotted a little later by parents or paediatricians (4, 5).

Radiological imaging is necessary to arrive at the proper diagnosis. A CT scan defines the osseal borders or the bony defect, and the size of the enlargement. MRI is needed to exclude the potential for intracranial extension, focusing on the meningeal integrity and the contact with frontal lobes. The only therapeutic option is surgery – complete excision is necessary to avoid a recurrence. There are various opinions in the literature about the best surgical approach and the timing of the operation. Treatment of the common dermoid cyst is usually not difficult but can be sporadic in adolescents and adults. Nasal dermoids can be removed through transcolumellar incision, as in open structure rhinoplasty, and osteotomy may also be required. The transfacial and transcranial approach, combined with the endoscopic transnasal approach, can be used as well. Neurosurgical evaluation is needed in case of suspected intracranial extension.

Three patients with dermoid nasal cysts and cutaneous fistula on the nasal dorsum are presented. 

MATERIALS AND RESULTS

We evaluated the diagnostic process and the surgical therapy effect at the University ENT Department, Bratislava, Slovakia during the years 2006–2009. We identified three patients, aged 15, 17 and 18, with nasal dermoid (1 girl and 2 boys) for this retrospective review. All of them had prior surgeries at different hospitals. None of the subjects had other associated anomalies, or intracranial extension.

Case 1

A 15-year-old girl underwent two preceding excisions of a nasal fistula. She presented with recurrent nasal swelling underneath the scar (Fig. 1). CT scan revealed a cystic formation between the frontal sinuses. The cyst has been clearly separated from the intracranium, and its canal continued to the nasal dorsum and the scar on the skin (Fig. 2.)

A total resection of both the fistula with the canal and the cyst was performed via dorsal incision. Part of the anterior wall of the frontal sinuses was opened, and after the medial osteotomy was preformed, the cavity was filled in with fat tissue (Fig. 3).

Case 2

A recurrent nasal enlargement after the resection of a nasal fistula (performed at a different hospital) was found in an 18-year-old boy (Fig. 4). The CT scans exposed the cystic formation under all the nasal bones without intracranial extension (Fig. 5). The cyst was removed using open rhinoplasty; the opening of the fistula on the skin stayed intact (Fig. 6).

Case 3

A couple of exstirpations of the nasal fistula were performed in a 17-year-old boy during his childhood (Fig. 7A). A residual opening with intermittent discharge formed on the nasal dorsum (Fig. 8). The CT scan showed a cystic formation without intracranial extension under the nasal bone. The open rhinoplasty technique with a resection of the dermoid cyst and its canal was performed with a gibbus resection and four osteotomies (Fig. 9). The skin scar stayed intact (Fig. 7B).

DISCUSSION

Case reports about nasal dermoids and their management are abundant in the medical literature. (6, 7, 8, 9). The optimal age for surgery is during the 5th and 6th years of life, when the risk of leaving a residual dermoid tissue is not as high (7). Exstirpation with an external, transfacial incision was commonly performed in the past for patients without intracranial involvement, but nowadays the transcolumellar incision with open rhinoplasty is recommended (10, 11, 15). This has become the standard procedure with regard to the functional and aesthetic aspects of the nasal surgery. Transnasal endoscopic resection is another option. If the nasal dermoid lies under the nasal bones and glabella, endoscopic procedures might be complicated. Moreover, transnasal endoscopic resection is generally not recommended for dermoids extending into or beyond the falx cerebri, or other brain structures (1).

Heywood et al. (12) suggest the use of a brow incision and a small window craniotomy as a successful low morbidity technique for the excision of nasal dermoids with intracranial extension.

For the surgical removal of nasal dermoids with intracranial extension, both the transglabellar subcranial approach (13) and the bicoronal incision with craniotomy (14) are effective. A total excision prevents a recurrence, but the cosmetic aspects of the excision have to be considered.

In the first case, an external approach directly through the fistulous aperture was used because the surrounding tissue was inflamed and scarred. The skin had to be excised and then sutured. After healing, the scar on the nasal dorsum was not very noticeable. We do not have post-surgical photographic documentation, as the patient did not come in for her 6-month follow-up visit. For the other two patients transcollumelar incision together with an open rhinoplasty was chosen. This approach is more convenient if the external orifice of the fistula is located inferiorly, or if the nasal dorsum has to be corrected due to being widened by an expansive cyst growth.

The open approach provides a sufficient overview in an operative context, and it makes it possible to perform osteotomies in order to narrow the nasal pyramid. The cyst and fistula can be completely removed, and the aesthetic result is good. The excision of the cyst can create a new preformed cavity which is not connected to the paransal sinuses and their draining system with the respiratory epithelium. In these cases, obliteration of such a cavity seems to be a good option. In order to perform fine exploration of nasal dermoid with a pleasing cosmetic effect, Bloom et al. (15) recommend external rhinoplasty as the surgical approach of choice. Different surgical techniques consist of the direct median approach and the paracanthal approach (16).

Pediatric otorhinolaryngologists usually deal with the surgical treatment of the nasal dermoid cysts and fistulas. These procedures are relatively rare in adolescents and adults. Delayed diagnosis may be caused by previous improper treatment. If a patient underwent excision of the external orifice and curretage of a fistula without having pre-operative imaging, physicians usually do not consider the diagnosis of a congenital nasal dermoid cyst. Cysts diagnosed later in life have a higher frequency of deep involvement and therefore require more extensive surgery (17).

Nasal dermoids must be differentiated from gliomas or encephaloceles, and the diagnosis must be confirmed with a CT scan or an MRI. An MRI is considered the most accurate way of evaluating nasal dermoids and is also essential for preoperative planning. 

CONCLUSION

Dermoid cysts are the most common midline congenital nasal masses and may extend intracranially. To make the proper diagnosis, radiological imaging with an evaluation of the intracranial structures should be obtained. Total exstirpation with an acceptable cosmetic result is the only causal therapy. Open rhinoplasty is one of the appropriate methods in patients without dural attachment or intracranial propagation of the nasal dermoid.  

Address for correspondence:

Ass. Prof. Pavel Doležal, M.D., PhD

Head of the E.N.T. Dept., Slovak Medical University

Antolská 11

851 07 Bratislava

Slovakia

E-mail: dolpavel@gmail.com