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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
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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.
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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
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