Full text of DOI:10.1111/j.1751-0813.2000.tb10583.x

Clinical
Dermoid cyst in the tongue of a dog
a
b
a
JM LIPTAK , PJ CANFIELD and GB HUNT
A German Shepherd Dog presented with recurrent intermandibular and intralingual swelling. Cytological and microbio-
logical findings on fluid aspirated from the mass were consistent with an infected cyst lined by epithelium. The sinus was
explored and an epithelium-lined cystic structure was extirpated from the frenulum and body of the tongue. This struc-
ture was diagnosed histologically as a dermoid cyst.
Aust Vet J 2000;78:160-161
Key Words: Dermoid cyst, tongue, congenital, dog
Case report
lining of the cyst near its junction with
intermandibular skin. The cyst was
traced along the ventral midline of the
tongue from the caudal third to the
rostral tip. It then turned 180° to extend
along the dorsal midline approximately
a third to half the length of the tongue
(Figure 3). The lyssa was grossly normal
and was not contiguous with the cyst.
The cyst was incised and removed using
a combination of sharp and blunt dissec-
tion (Figure 4). The mucosa of the
frenulum was sutured with 3-0
polyglactin in a single interrupted
pattern and the intermandibular sinus
tract was left open for dependent
drainage.
A 4-year-old, 32 kg, female neutered
German Shepherd Dog presented with a
swelling in the intermandibular area and
frenulum of the tongue. The swelling
had grown slowly over a 12 month
period. Incision by the referring veteri-
narian resulted in extrusion of a thick,
dark brown discharge composed of
amorphous granular viscid material
mixed with a few keratinised squamous
epithelial cells. A scar-like lesion was
observed on the dorsal midline of the
tongue. The swelling recurred 4 months
later and bled intermittently 7 d before
the dog was referred for further evalua-
tion.
On presentation, the dog had a scab
overlying a ventral swelling on the
midline of the intermandibular area.
The swelling was fluctuant and not
painful. Greenish fluid aspirated from
the mass was submitted for cytology and
bacterial culture and susceptibility
Histopathology of the cyst lining
revealed keratinised stratified squamous
epithelium and severe chronic inflam-
matory changes consistent with a
dermoid cyst and secondary infection.
Haemorrhagic discharge from the
draining sinus stopped 36 h following
surgery. Culture of the cystic fluid
showed a heavy mixed growth of
Staphylococcus intermedius and coliforms
and, on the basis of susceptibility results,
the dog was treated with amoxycillin-
clavulanate (500 mg orally every 8 h) for
7 d. The draining sinus healed without
complication and the cyst has not
recurred 16 months postoperatively.
Figure 1. Cytological preparation of a fine
needle aspirate from an intermandibular
swelling in a German Shepherd dog.
Keratinised squamous epithelium, degen-
erate inflammatory cells, acellular debris
and many forms of bacteria are present
(Diff-Quik stain, x 77).
testing.
Cytological
examination
revealed numerous keratinised squa-
mous epithelial cells, acellular debris,
occasional inflammatory cells with
pyknotic nuclei and many mixed forms
of extracellular bacteria (Figure 1).
The dog was anaesthetised to examine
the oral cavity. The lingual frenulum was
mildly swollen and a scar was present on
the dorsal midline of the tongue. A
probe inserted through the draining
sinus in the ventral midline of the inter-
mandibular area could be advanced into
the frenulum of the tongue (Figure 2).
The draining sinus was incised to
reveal an epithelium-lined cyst. Hairs
could be seen growing from the inner
Discussion
Developmental cysts have not previ-
ously been reported in the tongue of the
dog. However, a variety of conditions
are known to affect the tongue of
human patients. These include foregut
cyst, follicular cyst, dermoid cyst,
thyroglossal duct cyst, branchial cleft or
lymphoepithelial cyst, ranula, congenital
cystic choristoma, hydatid cyst, bron-
a
Department of Veterinary Clinical Sciences, The
University of Sydney, New South Wales 2006
Figure 2. A probe has been inserted
through the draining sinus in the inter-
mandibular area which extends into the
frenulum of the tongue.
b
Department of Veterinary Anatomy and
Pathology, The University of Sydney, New South
Wales 2006
1
chogenic cyst, and cystic hygroma.
160
Aust Vet J Vol 78, No 3, March 2000

Clinical
Figure 3. A diagrammatic representation of the location of the
dermoid cyst within the frenulum and body of the tongue.
Figure 4. The excised dermoid cyst. The 5 cm of the cyst to the
left of the picture was located within the body of the tongue, the
intermediate 2.5 cm was situated in the frenulum of the tongue,
and the remainder was excised from the intermandibular area.
submandibular space.1
Dermoid cysts reported in the inter-
mandibular area of a donkey and a calf
did not extend into the tongue.3,4 The
Cysts can be differentiated histologi-
cally on the basis of their lining but the
diagnosis can be complicated by chronic
inflammation and infection which
results in metaplasia of the epithelial
lining and formation of fibrovascular
Rapid healing with excellent func-
tional and cosmetic results are achieved
with surgical enucleation of develop-
mental lingual cysts regardless of their
1
most common dermoid cyst in dogs is
the dermoid or pilonidal sinus which is
an inherited cyst occurring along the
dorsal midline between the occipital
origin. Recurrence is due to incomplete
surgical excision and is usually evident
1
1
tissue. Ranulas do not have an epithe-
within 1 month of surgery. There has
lial lining. Foregut cysts result from
duplication of the embryonic alimentary
tract and are lined by a mucous
membrane of enteric origin. The lining
of thyroglossal duct cysts consists of
been no evidence of recurrence in this
dog 16 months following surgical exci-
sion.
2
crest and sacrum. Similar to the
dermoid cyst in the present case,
dermoid sinuses have a midline position
as a result of an abnormality in embryo-
genesis. Palpation is not painful unless
infection is present and the squamous
epithelial lining has adnexal structures
and occasional chronic inflammatory
changes caused by a foreign body reac-
tion to extruded cyst material and hair
Acknowledgments
pseudostratified, ciliated columnar epithe
-
The authors thank Dr Ffiona Phillips
for referring this case and Dr Elizabeth
Dill-Macky for assistance with case
management.
lium and stratified squamous epithe-
lium. Lymphoepithelial cysts are charac-
terised by a stratified squamous epithelia
lining with lymphocytic infiltration.
l
1
Dermoid cysts are usually lined by
stratified squamous epithelium and
adnexal structures and filled with kerati-
2
References
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2
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5
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(
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3
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lateral swellings of the branchial arches
1
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4
5
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1
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cysts are usually located in a midline
position. In humans, the head and neck
is the third most common site
accounting for 7% of cases. A quarter of
these involve the floor of the mouth and
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Accepted for publication 3 November 1999