OPEN ACCESS ATLAS OF OTOLARYNGOLOGY, HEAD &
NECK OPERATIVE SURGERY
SURGERY FOR NASAL DERMOIDS Hiba Al-Reefy, Claire Hopkins, Nico Jonas
Midline masses are rare congenital
anomalies, with an incidence reported to
be between 1 in 20,000 to 1 in 40,000 live
births. Nasal dermoid cysts are the most
common of the congenital midline nasal
masses, a group that also includes nasal
gliomas and encephalocoeles, and much
less frequently haemangiomas, lipomas,
lymphangiomas and other very rare
lesions. Cases are usually sporadic, but
rare familial series have been reported.
They are distinguished by the tissues of
origin, with dermoids developing from
trapped ectoderm and mesoderm; hence Figure 1: Dermoid cyst presenting as
they may contain adnexal structures such midline nasal mass
as skin, hair follicles and sebaceous glands.
By contrast, encephalocoeles are hernia-
tions of the meninges, and may also con-
tain brain tissue, while gliomas contain
glial cells.
Clinical presentation
Many dermoids present at birth, but some
present later in childhood or even adult-
hood when they become symptom- Figure 2: Nasofrontal sinus
tic. They typically present as an isolated
mass, a midline nasal deformity (Figure 1) nervous system has been variably reported
or as a sinus tract opening onto the skin, to occur in 4-45%. Suspicion of in intra-
(Figure 2). A midline nasal pit, fistula, or cranial involvement should remain high,
infected mass may be located anywhere and suspected lesions should not be
from the glabella to the nasal columella. It biopsied before radiological evaluation has
usually terminates in a single subcuta- been undertaken.
neous tract which may have hair at its
opening; this is said to be pathognomonic Although there is no known syndro-
of a dermoid. It may secrete sebaceous mic association, associated congenital ano-
material or pus, become intermittently in- malies occur in 5-41%; this includes aural
flamed, form an abscess, cause osteo- atresia, mental retardation, spinal column
myelitis, or present with nasal obstruction, abnormalities, hydrocephalus, hypertelo-
or with broadening of the nasal root or rism, hemifacial microsomia, albinism,
bridge. corpus callosum agenesis, cerebral atro-
phy, lumbar lipoma, dermal cyst of the
Occasionally it presents with intracranial frontal lobe, cleft lip and palate, tracheo-
complications such as meningitis or a cere- esophageal fistula, and coronary artery,
bral abscess. Connection with the central cardiac, genital, and cerebral anomalies.
Embryology
The nose is formed from the frontonasal
process and two nasal placodes which de-
velop dorsal to the stomodaeum (primitive
mouth) during the fourth week of
embryological life. The nasal placodes
consist of medial and lateral processes and a
become more prominent. The medial pro-
cesses approach one another and eventual-
ly fuse in the midline. The lateral processes
become less prominent as the maxillary
process fuses with them. A deep groove in
this region, called the nasal-maxillary
groove becomes the nasolacrimal duct. As
the external nose is develops, other neural
crest cells migrate through the frontonasal
process to form the posterior septum,
ethmoid bone, and sphenoid. The nasal
b
septum develops around week five from
the frontonasal process, growing in an
anterior-posterior direction.
During formation of the skull base and
nose, mesenchymal structures are formed
from several centers that eventually fuse
and begin to ossify. Before they fuse there
are recognised spaces between them that
are important in the development of
congenital midline nasal masses. These
include the fonticulus nasofrontalis, the
prenasal space, and the foramen caecum
(Figures 3a-c). The fonticulus frontalis is c
the space between the frontal and nasal
bones. The prenasal space is located
between the nasal bones and the nasal
capsule (precursor of nasal septum and
nasal cartilages). During foetal develop-
ment these spaces are close by fusing and Figure 3: (a) Fonticulus nasofrontalis and
ossifying. Abnormal development of these prenasal space; (b) Fonticulus frontalis
structures is thought to be involved in the closes, foramen caecum is formed, and a
formation of nasal dermoids. projection of dural diverticulum contacts
the tip of the nose; (c) Dural diverticulum
A widely accepted theory of dermoid sinus retracts and prenasal space is obliterated.
cyst development is the prenasal space (From: Barkovich AJ, et al. Congenital
theory. According to this theory, during nasal masses: CT and MR imaging fea-
normal development a projection of dura tures in 16 cases. Am J Neuroradiol 1991;
protrudes through the fonticulus frontalis 12:105-16)
2
or inferiorly into the prenasal space. This galli makes an intracranial connection
projection normally regresses but if it does unlikely. However, in order to exclude
not, the dura then remains attached to the this, MRI scanning is required and is
epidermis and result in trapped ecto- becoming the imaging method of choice,
dermal elements. as both false-positives and false-negatives
for intracranial involvement are found with
CT. It is prudent in many cases (especially
Pre-operative evaluation when a child requires general anaesthaesia
or sedation for imaging) to either obtain
Clinical evaluation both images at a single sitting or to
proceed directly to MRI scan (Figure 5).
Encephalocoeles are pulsatile, compressi-
ble masses that expand on crying and on
bilateral compression of the internal jugu-
lar veins (Furstenberg test); neither glio-
mas nor dermoids expand with crying or
the Furstenberg test. However a negative
Furstenberg test does not exclude intra-
cranial extension; hence imaging is essen-
tial.
Radiological Imaging
If a dermoid is suspected, imaging is man- Figure 5: MRI scan of nasal dermoid cyst
datory to determine the extent of the cyst
or tract, to exclude an intracranial con-
Surgery
nection and to plan surgery. A CT scan
delineates the bony anatomy and may
Early surgical intervention is recommend-
indicate an intracranial connection (Figure
ded to avoid further distortion of the nose
4).
or bony atrophy caused by growth of the
mass or recurrent infection. Biopsy is con-
traindicated due to risk of CSF leakage in
cases with intracranial connections. The
surgical objective is complete surgical ex-
cision at the first operation. Two factors
determine the surgical approach
• Is there an intracranial connection?
• What is the extent of the lesion?
The ideal surgical approach for extensive
dermoid cysts and tracts should permit
• Access to the whole cyst/tract
Figure 4: CT scan of nasal dermoid cyst • Medial and lateral osteotomies if
required
Features such as an intracranial soft tissue • Rapid repair of cribriform defects and
mass, a bifid crista galli, orbital widening CSF rhinorrhoea
or a cribiform plate defect are indicators of • Reconstruction of the nasal dorsum
intracranial extension. A normal crista with a minimally visible scar
3
Several surgical approaches have been
described; occasionally more than one
incision is required especially in the
presence of a nasal pit or skin breakdown
• Transverse rhinotomy
• Septorhinoplasty approach
• Vertical rhinotomy
• Horizontal nasofrontal incision with
eyebrow extensions
• Endoscopic approaches
Transverse rhinotomy: This can be used
for small to moderate-sized lesions without Figure 6: Stepped columella incision with
intracranial extension. The sinus punctum open septorhinoplasty approach
is excised within a transversely oriented
ellipse of skin and the tract is cannulated
with a lacrimal probe and dissect-
ed. Medial or lateral osteotomies may be
performed if necessary. If placed in a
natural nasal skin crease it leaves a very
favourable scar.
Open septorhinoplasty approach: This
provides wide exposure, but with a con-
cealed, aesthetically pleasing scar, for
larger lesions and for patients with dam-
aged bone and cartilage from prior surgery
or recurrent infection or with intracranial
extension. A separate excision of a sinus Figure 7: Full exposure of dermoid cyst
opening may be required; with intracranial
extension a combined intracranial ap- allows for the lower lateral cartilages to be
proach may be required. A stepped re-aligned if displaced laterally by a
columella incision is made to release the dermoid cyst extending to the nasal tip.
columella followed by bilateral marginal
incisions (Figure 6); the upper and lower If a large defect remains after surgery, a
lateral cartilages are delineated. A dermoid dorsal graft can be placed to restore
cyst may be adherent to the upper lateral volume without the presence of an
cartilages, dorsal septum and nasal bones; overlying incision line, thereby reducing
full exposure is mandatory to ensure risks of infection and extrusion. Grafts are
complete excision and to prevent recur- however often not required as the defect
rence (Figure 7). A nasal pit can be fills with scar tissue.
removed using a small elliptical skin
incision on the nasal dorsum. Extension of this approach to involve the
alar base allows for further exposure of the
An endoscope or operating microscope nasal dorsum as the skin envelope can be
may be used to facilitate more cephalad raised more cephalad (Figures 8, 9a, 9b).
dissections and to achieve complete resec-
tion. The open septorhinoplasty approach
4
Figure 8: Extended alar base incision
Figure 10: Vertical midline incision
Figure 9a: Further exposure allows com-
plete excision
Figure 11: Nasal dermoid tract
Horizontal nasofrontal incision: This is
reserved for cysts limited to the nasofrontal
area or to facilitate a small craniotomy to
remove the tract with intracranial exten-
sion. The incision can be extended along
the eyebrows to allow additional exposure
(Figure 12). Following removal of a cyst
(Figures 13a, b) a bony window can be
marked (Figure 14) to include the tract and
Figure 9b: Excised dermoid cyst allow access to the intracranial component.
A small cutting bur can be used to cut out
Midline vertical incision: This provides the bony window and allow direct access
excellent exposure as it can be extended to to the intracranial portion (Figure 15).
allow access to the skull base (Figures 10,
11).
5
Figure 12: Horizontal nasofrontal incision Figure 14: Bony window marked on outer
with eyebrow extensions table of skull
Figure 15: Small cutting burr used to cut
Figure 13a: Dermoid cyst visible in wound out bony window
Figure 16: Closed horizontal nasofrontal
Figure 13b: Skull exposed following exci- incision
sion; specimen (inset)
All facial incisions mentioned heal with
excellent cosmesis (Figure 16); the choice
6
of external surgical approach is therefore Postoperative complications
dictated principally by the size and site of
the dermoid, presence of a pit, and expe- • Tissue defect: Resecting a large der-
rience of the surgeon. moid may leave a significant soft tissue
defect, as well as splayed nasal bones.
Endoscopic approach: An endonasal en- Although osteotomies may be used to
doscopic approach is recommended when close the defect, there is often remark-
a dermoid is located within the nasal cavity able filling-in of the defect by scar
with little or no cutaneous involvement. It tissue. It is therefore the authors’ prac-
can be combined with a small external tice to splint the nose with plaster of
midline excision of the cutaneous punc- Paris, as following rhinoplasty, and to
tum. Although there are reports of ade- delay reconstructive procedures. This
quate visualisation of the skull base has the advantage of having no graft
through intercartilagenous incisions to material in situ should for revision
allow passage of an endoscope and instru- surgery for recurrence be required.
ments, intracranial extension is a relative • Complications associated with intra-
contraindication to endoscopic approaches. cranial extension
• Meningitis
• Cerebrospinal fluid leak
Dermoids with intracanial extension • Cavernous sinus thrombosis
• Sepsis: Soft tissue, osteomyelitis
Midline masses with an intracranial con- • Anosmia: With frontal craniotomy
nection usually require a combined ap-
• Recurrence: This may occur as a
proach with the help of a paediatric neuro-
delayed phenomenon if the cyst or the
surgeon. A frontal craniotomy is done via a
tract was not fully excised. Imaging
bicoronal incision with elevation of a peri-
should be repeated, paying particular
cranial flap to facilitate reconstruction. A
attention to the most cephalic extension
subcranial approach via transglabellar or
of the cyst. Rates of 4 - 12% in some
nasofrontal incisions with eyebrow exten-
larger series, and up to 100%, have
sions and minicraniotomy as described
been reported
above may be preferred so as to avoid
frontal lobe retraction. Once the intracra-
nial component has been excised, dural
Key Points
and bony defects are repaired. The extra-
cranial mass may require a separate
• The primary aim is complete surgical
approach using the incisions described
excision at the first operation
previously to permit complete removal.
• Biopsy is contraindicated due to the
Where intracranial communication has risk of CSF leakage in cases with
been neither excluded nor confirmed, an intracranial connections
external approach is initially undertaken. • Early surgical intervention is recom-
The tract may be followed to its dural mended to avoid further nasal distor-
attachment at the foramen caecum where tion and bony atrophy due to growth of
biopsies can be taken. If dermal or the mass or recurrent infection
epidermal elements are identified in the • The surgical approach is determined by
biopsy, frontal craniotomy is indicated; if the extent of the lesion and the
only fibrous tissue is present then excision presence of an intracranial connection
is complete.
7
Authors
Hiba Al-Reefy MBChB, DOHNS, FRCS
(ORL-HNS)
Specialist Registrar
Otolaryngology, Head and Neck Surgery
Guys and St. Thomas’ Hospital
London, United Kingdom
drhibaalreefy@hotmail.com
Claire Hopkins BMBCh, MA (Oxon),
FRCS (ORL-HNS), DM
Rhinologist, Skull Base Surgeon
Guys and St. Thomas’ Hospital
London, United Kingdom
clairehopkins@yahoo.com
Author and Paediatric Section Editor
Nico Jonas MBChB, FCORL, MMed
Paediatric Otolaryngologist
Addenbrooke’s Hospital
Cambridge, United Kingdom
nico.jonas@gmail.com
Editor
Johan Fagan MBChB, FCORL, MMed
Professor and Chairman
Division of Otolaryngology
University of Cape Town
Cape Town, South Africa
johannes.fagan@uct.ac.za
THE OPEN ACCESS ATLAS OF
OTOLARYNGOLOGY, HEAD &
NECK OPERATIVE SURGERY
www.entdev.uct.ac.za
The Open Access Atlas of Otolaryngology, Head &
Neck Operative Surgery by Johan Fagan (Editor)
johannes.fagan@uct.ac.za is licensed under a Creative
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