International Journal of Clinical Case Reports 2015, Vol.5, No. 42, 1-6
5
and was initially referred for opinion and biopsy as
swelling didn’t subside for long. This type of cyst
tends to expand in an antero-posterior direction within
the medullary cavity of the bone without causing
obvious bone expansion and this unique feature often
becomes useful in its clinical and radiographic
diagnosis because dentigerous and radicular cysts of
comparable size are usually associated with bony
expansion (Neville et al., 2002; Hiremath et al., 2011)
which was not similar to our clinical finding in this
case. Radiographically, OKCs appear as well-defined
radiolucencies, which can be either unilocular or
multilocular. They typically extend into the marrow
cavity with either a smooth border contributing to
mild bulging of the cortex but without significant
cortical expansion. Keratocystic odontogenic tumors
can show a more aggressive growth pattern including
multilocularity, cortical expansion, perforation of the
cortical bone, tooth and mandibular canal displacement,
root resorption, and extrusion of erupted teeth
(Devenney-Cakir et al., 2011). Unilocular OKCs can
be located periapically, simulating periapical cysts;
between the roots of teeth, simulating lateral
periodontal cysts or lateral radicular cysts; surrounding
the crown of unerupted teeth, simulating dentigerous
cysts; or in the maxillary midline, simulating
nasopalatine duct cysts. Large unilocular OKCs can be
impossible to tell apart from cystic ameloblastomas.
OKCs have a tendency for intra-osseous growth, more
often in a longitudinal than in a transverse direction
(minimal expansion), as seen in this case, thereby
replacing the bone marrow, rather than giving rise to
periosteal bone formation, which would result in a
bony swelling. Rapid growth does not allow enough
time for the periosteum to lay down new bone. These
different types of appearances of OKC make diagnosis
more dilemmatic as in our present case. The luminal
content can have different consistencies described as a
“straw-colored fluid”, “thick pus-like” material or a
caseous, thick, cheesy, milk white mass (Rajkumar et
al., 2011). But in our case aspiration finding was
exclusively different which were more suggestive of
an aspirate from arterio-venous malformations or
Aneurysmal Bone Cyst. Histologically, KCOTs have
been classified by some authors into parakeratotic and
orthokeratotic subtypes. Classification is based on the
lining and the type of keratin produced. Compared
with the parakeratotic subtype, the orthokeratotic
subtype produces keratin more closely resembling the
normal keratin produced by the skin, with a
keratohyaline granular layer immediately adjacent to
the layers of keratin, which do not contain nuclei. The
parakeratotic subtype has more disordered production
of keratin; no keratohyaline granules are present, and
cells slough into the keratin layer. However, in case of
OKCs the lining epithelium is highly characteristic
and consists of keratinized surface (parakeratinized-
83% and orthokeratinized-10%) which is typically
corrugated. Thickness of the epithelium is found
uniformly arranged with 6 to 10 layers without
rete-ridges (Çakur et al., 2008).The keratin contains
nuclei and is referred to as parakeratin. The parakeratotic
type is the most frequent (80%) and has a more
aggressive clinical presentation than the orthokeratotic
variant. Histopathological picture shows presence of a
well defined, often palisaded, basal layer consisting of
columnar or cuboidal cells; intensely basophilic nuclei
of columnar basal cells oriented away from the
basement membrane; parakeratotic layers, often with a
corrugated surface; and mitotic figures frequently
present in suprabasal layers (Çakur et al., 2008;
Scartezini et al., 2012). This palisade like arrangement
of basal layer is often described as “picket fence” or
“tombstone” appearance. Upper portion of the epithelium
is composed of stratified squamous epithelium with
high mitotic index without any clear cell formation.
Epithelial plaque formation is absent in OKCs but the
connective tissue wall often shows small islands of
epithelium (Hiremath et al., 2011). OKCs have a high
recurrence rate ranging from 2.5 to 62 % (Sulabha et
al., 2013; Hiremath et al., 2011) and after they occur
due to incomplete removal of the original cyst’s lining,
thin friable cystic lining, growth of the new OKC
from small satellite cyst of odontogenic epithelial cell
rests left behind after surgical treatment, or by
development of an unrelated OKC in an adjacent
region of jaw which is interpreted as a recurrence
(Rajkumar et al., 2011; Sulabha et al., 2013). The
recurrence of OKC is thought to be based on great
mitotic activity and growth potential found in
epithelium, further than other sources of recurrences
such as remnants of dental lamina and epithelial
islands (Silvaa et al., 2006). There is no doubt that
recurrences may arise if any part of the lining is left
behind. All efforts should, therefore, be made at
proper enucleation and elimination of possible
remnants of the cyst wall in case the cyst ruptures and
has to be removed piecemeal. There is also a possibility
