Calcifying Odontogenic Cyst Associated with an Orthokeratinized
Vanessa de Fa ´tima Bernardes Æ Æ Ju ´lio Ce ´sar Tanos de Lacerda Æ Æ
Maria Ca ´ssia Ferreira de Aguiar Æ Æ Ricardo Santiago Gomez
Received: 19 June 2008/Accepted: 16 July 2008/Published online: 31 July 2008
? The Author(s) 2008
distinct types of lesions are unusual. In this paper, a case of
an odontogenic lesion characterized by simultaneous
occurrence of areas of calcifying odontogenic cyst (COC)
and orthokeratinized odontogenic cyst (OOC) is described.
The lesion was asymptomatic and presented at the radio-
radiolucency extending from left incisor to right premolar
area in the mandible. To date, this is the first report of COC
associated with an OOC.
Odontogenic tumors composed of two or more
Orthokeratinized odontogenic cyst ? Odontogenic cyst ?
Calcifying odontogenic cyst ?
Odontogenictumors composed oftwoormoredistincttypes
of lesions are unusual and the biologic mechanism causing
such a unique combination is not readily apparent .
The calcifying odontogenic cyst (COC) was first defined
as a separate entity in 1962 . According to the new
WHO classification in 2005 COC has now been reclassified
as calcifying cystic odontogenic tumor (CCOT) .
Although there is no consensus regarding the classification
and terminology of COC, this benign lesion is categorized
as either a cyst or neoplasm (solid) [3–5]. In the cyst var-
iant, three different types may be found: simple unicystic
type, unicystic odontoma-associated type, and unicystic
ameloblastomatous proliferating type. COC is usually
asymptomatic and may be an incidental radiographic
finding . Radiographically, the lesion appears as a uni-
locular or multilocular well-defined radiolucency that may
contain small irregular calcified bodies of varying sizes,
and it may be associated with an odontoma or an unerupted
tooth [2, 4].
The orthokeratinized odontogenic cyst (OOC) was first
described in 1927 as a dermoid cyst  and in 1945 it was
considered as an eventual type of odontogenic keratocyst
(OKC) . In 1981, Wright  specified its clinicopatho-
logic aspects, assuring that OOC was an individual entity,
distinct from other odontogenic cysts, including the OKC.
OOC has been described as a solitary lesion, usually small
and nonexpanding, radiolucent, and asymptomatic .
In this article, a COC associated with an OOC is
described. As far as we are concerned, this is the first case
reported in the English-language literature.
A 24-year-old woman was referred to the Oral Diagnosis
Service of Odilon Behrens Hospital for consultation
regarding a radiolucent lesion in mandible. The lesion was
asymptomatic and a discrete swelling was noted in the
V. de Fa ´tima Bernardes
DDS, Department of Oral Surgery and Pathology, School of
Dentistry, Universidade Federal de Minas Gerais, Belo
Horizonte, MG, Brazil
J. C. T. de Lacerda
Oral and Maxillofacial Surgeon, Odilon Behrens Hospital,
Belo Horizonte, MG, Brazil
M. C. F. de Aguiar ? R. S. Gomez (&)
Department of Oral Surgery and Pathology, School of Dentistry,
Faculdade de Odontologia da UFMG, Universidade Federal de
Minas Gerais, Av. Anto ˆnio Carlos, 6627 Pampulha,
Belo Horizonte, MG CEP 31270-901, Brazil
Head and Neck Pathol (2008) 2:324–327
region. The overlying mucosa was normal, and radiological
findings revealed a unilocular well-delimited radiolucency
with delicate septae extending from first lower left pre-
molar to lower right lateral incisor (Fig. 1a). The vitality
test revealed that all teeth were vital. Aspiration of the
lesion provided a viscous content presenting creamy
material composed of keratin intermingled by yellowish
granules. Considering a provisional diagnosis of an odon-
togenic benign lesion an excisional biopsy was performed.
Grossly, the material presented an oval format with a cystic
cavity containing yellowish granules. Histopathological
examination revealed a cystic lesion presenting a fibrous
capsule lined with odontogenic epithelium of variable
thickness. Cuboidal and columnar cells resembling a-
meloblasts were observed at the basal layer. Above the
basal layer, the epithelial cells showed a loose arrangement
together with groups of ghost cells (Fig. 1b, c). It was
observed a transition from COC to OOC in which the
lining was represented by orthokeratinized stratified epi-
thelium with uniform thickness (Fig. 1d, e). In addition,
Fig. 1 (a) Radiological
findings of the lesion; (b)
Histopathological features of
COC with ghost cells (HE
1009); (c) Columnar cells
resembling ameloblasts at the
basal layer and the epithelial
cells with a loose arrangement
above the basal layer (HE
4009); (d) Transition from
COC to OOC (HE 4009); (e)
Histopathological features of
OOC showing orthokeratinized
stratified epithelium (HE
4009); (f) Ameloblastomatous
proliferation in the fibrous
capsule (HE 4009)
Head and Neck Pathol (2008) 2:324–327325
ameloblastomatous proliferation was seen in the connec-
tive tissue (Fig. 1f). The COC represented about 70% of
the lesion. The final diagnosis was COC associated with an
OOC. There was no evidence of recurrence 5 months after
the enucleation of the lesion.
Hybrid odontogenic tumors have been reported occasion-
ally; most of these tumors have been diagnosed as an
odontogenic tumor (most commonly odontomas, amelobl-
astomas, ameloblastic fibroma) combined with COC [1, 10,
11]. However, an association of COC with an OOC has not
been described yet.
We suggest that the presence of two distinctive epithelial
odontogenic patterns, present in a single lesion, is probably
not a collision of a COC and an OOC, but it is instead an
epithelium from which these lesions are derived. This
assumption is supported by the finding of both histological
types lining the same cystic cavity. As COC is more undif-
the epithelium lining of the later, but the possibility of COC
mimicking OOC should also be considered.
OOC has been specified as an individual entity, distinct
from other odontogenic cysts, including OKC . OOC is
characterized by the presence of an epithelium-lined cavity
in which a significant portion of the epithelium exhibited
orthokeratinization and in which the basal cells showed
little tendency to palisade or polarize. Frequently, there is a
granular cell layer associated with the orthokeratin. The
intraosseous occurrence within the jaws, predilection for
the posterior mandible areas and the ability to keratinize in
their linings suggested initially that OOCs may share the
same histogenic origin as OKCs (from dental lamina and
its remnants) . However, many investigations have
demonstrated significant differences in histological features
and clinical behavior between OKC and OOC [13, 14]. In
addition, PTCH gene alterations commonly described in
OKC  have not been demonstrated in OOC. Mutation
on the b-catenin gene was previously reported in COC
, but has not been investigated in OOC. Molecular
studies are necessary to understand the histopathological
changes observed in the current case.
The present paper shows an example of the importance
of microscopic analysis of the entire specimen when
studying odontogenic cysts or tumors in general. The
treatment of COC involves simple enucleation of the lesion
and long-term follow-up. In most cases, the prognosis is
good, but in cases of solid neoplastic COC, recurrence is
more prone to occur. When it is present in association with
other odontogenic tumors, the treatment is based on the
associated tumor . Referring to behavior of OOC,
although it can become relatively large, this lesion seems to
be less aggressive than OKC .
fellows of CNPq (Conselho Nacional de Desenvolvimento Cientı ´fico
e Tecnolo ´gico)—Brazil.
Dr. RS Gomez and MCF Aguiar are research
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