8/17/2019 1-s2.0-S0165587611001303-main

1/3

Case report

Dermoid cyst in the facial nerve—A unique diagnosis

Raphael Nwojo a,*, Soham Roy a,1, C.Y. Joseph Chang b

a Department of Otorhinolaryngology, University of Texas, Medical School at Houston, 6431 Fannin Street, TX 77030, United Statesb Texas ENT Associates, Houston, TX, United States

1. Introduction

Facial nerve paralysis in children mayoccuras a complicationof 

infections, trauma, or rarely from benign or malignant tumors of 

the facial nerve. We present the first reported case of a dermoid

tumor in the facial nerve causing facial paralysis in a child.

Dermoid cysts are developmental malformations formed from

mesodermal and ectodermal origins. They may contain skin, hair

and adnexal structures. In general, dermoid cysts of the head and

neck region are a relatively rare occurrence and account for only

6.9% of all dermoid cysts   [1]. They predominantly occur in the

nasal, orbital and oral regions of the face. However, a dermoid cyst

in the facial nerve is extremely rare, and for this reason is difficult

to diagnose and may be misdiagnosed as Bell’s palsy. We present acase of a facial nerve dermoid cyst with a review of the literature.

2. Case report

A previously healthy 9-month-old male presented with right-

sided facial paralysis of gradual onset, which progressed to a

complete facial paralysis over a 2 week period. He had no prior

upper respiratory symptoms, but did develop an upper

respiratory infection one week after the onset of his facial

paralysis. Over the 3 months prior to presentation, his right

facial paralysis did not improve or change. He had no history of 

ear infections, head trauma or other systemic symptoms. He was

not treated with any antibiotics, steroids, or antiviral medica-

tion. Physical examination revealed obvious right-sided facial

nerve paralysis with a House-Brackmann grade 6/6. The

remainder of his exam was unremarkable. CT scan of the

temporal bones showed marked enlargement of the right facial

nerve canal in its second genu and vertical portion measuring

6.6 mm (Fig. 1). A soft tissue mass was visible extruding from

the pyramid into the middle ear cavity, contacting the longprocess of the incus just above the incudostapedial joint. His

stapes itself was not contacted by the mass, and the ossicles

were otherwise normal. His proximal facial nerve canal was

normal. The TM was also normal. An MRI of the IACs identified a

normal appearance of cranial nerve VII and CN VIII within the

internal auditory canals and in the cisternal segments (Fig. 2).

Correlating with the abnormality seen on the CT temporal bone

scan, there was an isointense lesion of the right mastoid

segment of the facial nerve on T1 with hyperintensity on T2

imaging. The lesion extended into the middle ear cavity

enlarging the mastoid segment of the facial nerve canal.

International Journal of Pediatric Otorhinolaryngology 75 (2011) 874–876

A R T I C L E I N F O

 Article history:

Received 7 December 2010

Received in revised form 23 March 2011

Accepted 24 March 2011Available online 22 April 2011

Keywords:

Dermoid

Facial nerve

Facial nerve paralysis

Pediatric

Otology

A B S T R A C T

Facialnerveparalysis in childrenmay occur asa complication of infections, trauma, or rarelyfrombenign

or malignant tumors of the facial nerve. We present the first reported case of a dermoid tumor in the

facialnervecausing facial paralysisin a child.Case reportat a tertiary Children’s Hospital.A 9-month-old

was referred to our institution for evaluation of persistent, complete right sided facial paralysis three

months after receiving a diagnosis of Bell’s palsy. A workup at our institution including MRI and CT

revealed marked widening of the facial canal in the mastoid segment consistent with facial nerve

schwannoma or hemangioma. Surgical exploration via mastoidectomy and facial nerve decompression

revealed keratinous material containing hair that had fully eroded the facial nerve, disrupting it

completely. The entire tumor was removed along with the involved segment of facial nerve, and the

missing facial nerve segment was cable grafted. Histological examination of the tumor confirmed a

ruptured dermoid cyst in the facial nerve. Facial nerve tumors are rare causes of facial paralysis in

children, accounting for fewer than 10% of cases of facial paralysis in the pediatric population. Dermoid

cyst can occur throughout the head and neck region in children, but a dermoid tumor in the facial nerve

has not been described in the literature prior to this report. This represents a new and uncommon

diagnostic entity in the evaluation of facial nerve paralysis in children. Appropriate imaging studies and

pathology slides will be reviewed.

 2011 Elsevier Ireland Ltd. All rights reserved.

* Corresponding author. Tel.: +1 832 865 0320.

E-mail addresses:   rnwojo@hotmail.com (R. Nwojo),  soham.roy@uth.tmc.edu

(S. Roy),  drchang@texasent.com (C.Y. Joseph Chang).1 Tel: +1 713 500 5410; fax: +1 713 383 3277.

Contents lists available at  ScienceDirect

International Journal of Pediatric Otorhinolaryngology

j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / i j p o r l

0165-5876/$ – see front matter    2011 Elsevier Ireland Ltd. All rights reserved.

doi:10.1016/j.ijporl.2011.03.018

http://dx.doi.org/10.1016/j.ijporl.2011.03.018mailto:rnwojo@hotmail.commailto:soham.roy@uth.tmc.edumailto:drchang@texasent.comhttp://www.sciencedirect.com/science/journal/01655876http://dx.doi.org/10.1016/j.ijporl.2011.03.018http://dx.doi.org/10.1016/j.ijporl.2011.03.018http://www.sciencedirect.com/science/journal/01655876mailto:drchang@texasent.commailto:soham.roy@uth.tmc.edumailto:rnwojo@hotmail.comhttp://dx.doi.org/10.1016/j.ijporl.2011.03.018

8/17/2019 1-s2.0-S0165587611001303-main

2/3

Based on the concerning appearance of the mastoid segment of 

the facial nerve, the child underwent a mastoidectomy with

decompression of the facial nerve with facial nerve monitoring.

Intraoperatively, a large tumor was identified encompassing the

entire fallopian canal from the second genu to the stylomastoid

foramen. A fleshy portion of the tumor extended anteriorly into the

facial recess andthe posterior tympanic membrane in the regionof theoval window niche.Squamousdebris which also containedhair

and cheese-like material filled the posterior and medial portion of 

the fallopian canal (Fig. 3). The fallopian canal and the mastoid

segment of the facial nerve were absent, replaced by tumor. The

tumor was completely resected, and a nerve graft from proximal

facial nerve to distal nerve at the stylomastoid foramen was

performed using a sural nerve graft. His ossicular chain was noted

to be intact and the middle ear was free from of any other

abnormalities. Histological examination by pathology confirmed

the specimen to be a ruptured dermoid cyst (Fig. 4). On follow-up

at 10 months, the patient was doing well with facialnerve recovery

and a House-Brackmann grade of 3/6.

3. Discussion

Facial nerve palsy in children can be congenital or acquired. The

differential diagnosis of facial nerve palsy or paralysis in children

includes infectious etiologies (most commonly otitis media),

traumatic, idiopathic and congenital causes. An active middle

ear disease or a parotid mass has been reported to sometimes

present with facial nerve paralysis [4]. A diagnosis of Bell’s palsy is

equivocal if some facial function, however small, has not returned

within three to four months [2]. A slowlyprogressive, prolonged or

relapsing course suggests more ominous prognosis, such as

neoplasm, especially if paralysis persists without evidence of 

recovery  [3]. A discrete involvement of only one or two distal

branches of the facial nerve also is suggestive of neoplastic

etiology.In the evaluation of facial paralysis, imaging is indicated when

the physical signs are atypical, paralysis is slowly progressive

beyondthreeweeks, or if there is no improvementafter six months

[3]. In patients presenting with clinically complete facial paralysis,

electrodiagnostic studies may be useful in predicting prognosis [7].

MRI and CT can show the exact location of the lesion and the

relationship to the surrounding tissues, which may help with

diagnosis and surgical management; however these imaging

studies cannot give a final preoperative diagnosis  [5].

New and Erich classified dermoid cysts into 3 groupings based

on microscopic appearance and pathogenesis [6]. Thefirst category

of congenital dermoid cyst is the teratoma type arising from

embryonic germinal epithelium. The second category is the

acquired dermoid cysts which are a result of traumatic implanta-

[

Fig. 1. CT scan of temporal bones showing an enlargement of the facial nerve in the

vertical portion of the facial nerve canal (open arrow head).[

Fig. 2. MRI brain showing hyperintensity of right facial nerve (open arrow head) in

the mastoid segment.

[

Fig. 3.  Intraoperative picture of the destroyed facial nerve in the fallopian canal.

[

Fig. 4.   Pathology slide showing segment of resected facial nerve with abundant

keratinous debris and giant cell reaction consisted with a ruptured dermoid cyst.

R. Nwojo et al. / International Journal of Pediatric Otorhinolaryngology 75 (2011) 874–876    875

8/17/2019 1-s2.0-S0165587611001303-main

3/3

tion of skin in deeper layers, and the final category of cysts is the

congenital inclusion dermoid cyst which is particularly of interest

in the head and neck region [1]. The third group is further divided

into four subgroups according to anatomic location and embryo-

genesis: (1) cysts about the eyes and orbits, originating along the

nasooptic groove; (2) cysts about the nose, which resulted from

intrusion of the frontonasal plate; (3) cysts about the floor of the

mouth and in the submental and submaxillary regions, originating

from the upper branchial arches; (4) a miscellaneous group, most

of which occur at the mid-ventral or mid-dorsal lines of the body

[1]. Most dermoid cysts in the head and neck region occur around

the orbital, oral and nasal regions (80%); of these orbit tumors

involve 49.5%, nasal tumors 12.6%, submental and submaxillary

dermoids account for 23% and the remainder 14.6%  [6]. Dermoid

cysts are prone to form in these locations because they are the

fusion sites of many embryonic structures [6]. Dermoid cysts in the

facial nerve are difficult to categorize, as they do not fit into any of 

the classes or subclasses described above. Dermoid cysts are made

up of a variety of a parenchymal cell types representative of all

three germ cell layers. They are known to differentiate along

ectodermal lines to create a cystic tumor lined by skin filled with

hair, tooth structures and sebaceous glands.

The differential diagnosis of facial nerve tumors should include

hemangioma, facial nerve schwannoma, adenoma and endolym-phatic sac tumor   [9]. A true diagnosis of facial nerve dermoid

presently can only be made intraoperatively by histopathological

examination of tissue [8]. However, MRI and CT scan may be useful

in both finding the location of the tumor and its characteristics.

Dermoids, in particular, result in expansile lesions without

significant bony erosion identified on imaging. The use of fine

needle aspiration preoperatively was impractical in this case due

to the location of the lesion. Ultimately, diagnosis is confirmed by

final permanentpathology. Thegoal in surgical management of the

facial nerve dermoid tumor, like other dermoid tumors, involves

total extirpation of the entire cyst and contents to prevent

recurrence, including resection of the involved segment of nerve if 

the nerve cannot be preserved.

4. Conclusions

Facial nerve tumors are rare causes of facial paralysis in

children, accounting for fewer than 10% of cases of facial paralysisin the pediatric population. Dermoid cysts can occur throughout

the head and neck region in children, but a dermoid tumor in the

facial nerve has not been described in the literature prior to this

report. This represents a new and uncommon diagnostic entity in

the evaluation of facial nerve paralysis in children.

N.B. Signed parental consent was obtained for the use of 

imaging and intraoperative photographs for this paper.

References

[1] Eun-chang Choi, Jong-Boo Jin, Jin-Yong Kim, Dermoid cyst of the parotid gland,Yonsei Med. J. 29 (2) (1988).

[2] G.T. Hashisaki, Medical management of Bell’s palsy, Compr. Ther. 23 (1997) 715.[3] D.O. Boahene, K.D. Olsen, C. Driscoll, et al., Facial nerve paralysis secondary to

occult malignant neoplasms, Otolaryngol. Head Neck Surg. 130 (2004) 459.[4] M.May, G.B.Hughes,Facialnerve disorders: update1987, Am.J. Otol.8 (1987)167.[5] C. Naujoks, J. Handschel, S. Braunstein, F. Emaetig, R. Depprich, U. Meyer, et al.,

Dermoid cyst of the parotid gland – a case report and brief review of the literature,Int. J. Oral maxillofac. Surg. 36 (2007) 861–863.

[6] G.B. New, J.B. Erich, Dermoid cysts of the head and neck, Surg. Gynecol. Obstet. 65(1937) 48.

[7] J.S. Sillman, Prognostic value of evoked and standard electromyography in acutefacial paralysis, Otolaryngol. Head Neck Surg. 107 (1992) 377.

[8] D.O. Noahene, K.D. Olsen, C. Driscoll, et al., Facial nerve paralysis secondary tooccult malignant neoplasms, Otolaryngol. Head Neck Surg. 130 (2004) 459.

[9] M. May, S.R. Klein, Differential diagnosis of facial nerve palsy, Otolaryngol. Clin.North Am. 24 (1991) 613.

R. Nwojo et al. / International Journal of Pediatric Otorhinolaryngology 75 (2011) 874–876 876