1. 9 D][:Ir162 Ii[ I
PATHOLOGY
Cysts and cystic lesions of the jaws
P. R. Morgan
In this article, some recent findings on benign cysts and cystic neoplasms of odontogenic origin are
reviewed with special regard to their diagnostic relevance. Emphasis is given to less common lesions
and those which present diagnostic difficulty or which may involve more complex management.
Some recent applied research contributions in this area will also be included.
Introduction odontogenic cysts and tumours. Whilst all cysts lined
by stratified epithelium contain the primary keratins of
The jaws are unique in the skeleton in the amount and
keratinocytes, 5 and 14, keratocysts express keratins 1
variety of epithelial residues contained within them and
and 10 (markers of cornification) as well as 4 and 13
in the range of cystic lesions to which they give rise.
(markers of non-cornified epithelium). Dentigerous and
Management of such lesions is a significant proportion
radicular cysts also express keratins 4 and 13. Keratin
of the work-load of oral and maxillofacial surgeons
19 is expressed in odontogenic epithelia under all cir-
and relies on good pre-operative interpretation of radio-
cumstances, normal development, adult vestiges, cysts
graphs and computerised tomography (CT) scans and
and neoplasms (Fig. 1). Indeed, its presence is so con-
accurate histopathological diagnosis of biopsy and surgi-
sistent that it could be considered an obligatory keratin
cal specimens. To some extent, it is artificial to separate
of odontogenic epithelium and has the potential to be
the histopathological features from clinical and radio-
of diagnostic value. 5 Keratins 8 and 18, found in abun-
logical appearances when considering these lesions, as in
dance in simple epithelia, are expressed at low but vari-
other, longer reviews in this area 1,2and therefore descrip-
tions will not always be confined to histopathology.
For the purposes of this account, cysts will be divided
into benign cysts of odontogenic and non-odontogenic
origin and cystic neoplasms (benign and malignant).
Non-epithelial lined cysts will be mentioned briefly.
General characteristics of odontogenic epithelium
From the range and complexity of normal structures and
pathological lesions to which it gives rise, odontogenic
epithelium must be regarded as pluripotent? This is
borne out by the repertoire of keratin proteins which are
expressed in the developing normal tooth germ4 and in
Fig. 1--A frozen section of an odontogenic keratocyst
P. R. Morgan, BSc, BDS, PhD, MRCPath, Departmentof Oral stained with a monoclonal antibody to demonstrate keratin
Medicine & Pathology,UMDS, Floor 28, Guy's Tower, Guy's 19, present in all odontogenic epithelia. Streptavidin-biotin
Hospital, London SE1 9RT, UK peroxidase reaction,
Current Diagnostic Pathology (1995) 2, 86-93
9 1995 Pearson Professional Ltd 86

2. CYSTS AND CYSTIC LESIONSOF THE JAWS 87
Table-~Simplified classification of jaw cysts
ODONTOGENICCYSTS
Developmental
Dentigerous cyst
Eruption cyst
Odontogenic keratocyst
Lateral periodontal cyst
Botryoid odontogeniccyst
Glandular odontogeniccyst
Inflammatory
Radicular cyst, lateral radicular cyst, residual cyst, paradental cyst
NON-ODONTOGENICCYSTS
Nasopalatine duct cyst
'Fissural' cyst
CYSTIC NEOPLASMS
Ameloblastoma
Fig. 2 - - H y a l i n e bodies in the lining of a radicular cyst. Unicystic ameloblastoma
These structures are probably a secretion product, unique Calcifying odontogeniccyst
to o d o n t o g e n i c epithelia and similar to enamel cuticle,
which may be deposited concentrically on a 'template'
layer. H&E.
completion of tooth development and eruption. A major
division into developmental 13 and inflammatory catego-
able levels in keratinocytes of odontogenic cysts, apart ries is usual.
from keratocysts, and of course in zones of mucous
metaplasia.
Dentigerous cyst (follicular cyst)
Hyaline bodies (Rushton bodies) are highly eosino-
philic, laminated, circular or folded elongate structures This cyst is diagnosed by its precise relationship with the
(Fig. 2) which lie in the epithelium of about 10 per cent crown of an unerupted tooth, commonly the lower third
of all forms of odontogenic cyst but do not occur in other molar or upper permanent canine. Being derived from
cyst types. There is considerable evidence now that they the reduced enamel epithelium, the remnant of the
represent a secretion product, probably similar to dental enamel organ, it is attached to the tooth at the enamel-
cuticle which is deposited in variable amounts on tooth cementum junction (Fig. 3A). It is therefore important
enamel at the completion of its formation. The available for diagnosis that the tooth is supplied with the soft
histological, histochemical and ultrastructural evidence tissue specimen, or at least that accurate clinical inlor-
supports the view that it is a product of odontogenic epi- marion is supplied by the operator. Radiographically,
thelium secreted on to a template of endogenous or they are unitocular but the illusion of a dentigcrous
exogenous origin e.g. cholesterol crystal, root fragment cyst on a radiograph can be given by other radiolucent
or root filling material)When present, hyaline bodies lesions which may secondarily involve or displace an
may therefore be considered a marker of odontogenic unerupted looth, such as an ameloblastoma (see below).
cysts. Histologically, the cyst lining is characterised by
uniform, non-keratinised epithelium, either stratified
squamous about 4 10 cells thick or with a cuboidal basal
Cyst growth
layer, thus often resembling reduced enamel epithelium.
There is a considerable literature on possible mecha- Mucous metaplasia is frequently encotmtered (Fig. 3B).
nisms of cyst initiation and subsequent enlargement. 7 In the young patient, the wall is myxoid and contains
Theories have ranged from the osmotic/hydrostatic clusters of odontogenic epithelial rests and in more
pressure concept of Toiler s to differential growth 9 and mature follicles these often show cementicle-like miner-
inflammatory mediators such as prostaglandins m and, alisation. The immature, myxoid follicle has been vari-
more recently, interleukins. ~ There is little doubt that ously misdiagnosed as odontogenic cyst, myxoma,
fluid-filled cysts are under positive hydrostatic pressure odontogenic fibroma, odontome and even ameloblas-
but it may be doubtful whether this is transmitted as toma.~4 Rests of odontogenic epithelium in the wall may
a resorptive force to the surrounding bone, especially also form squamous pearls such as are found in greater
as the cell population of most cyst walls includes profusion in the squamous odontogenic tumour. In such
myofibroblasts which may serve to contain the pressure pearls basal cells are inconspicuous and mitoses exceed-
generated. ~2 ingly rare. It is not always possible to establish the point
A simple classification of jaw cysts 1,2 groups them at which an enlarged follicle becomes a dentigerous
broadly according to pathogenesis, with odontogenic cyst. Although there is rarely unanimity, a practical
cysts making up the largest proportion (Table). guide to the diagnosis of a cyst is a follicular space of
5 mm or more on a radiograph and a lining of stratified
squamous epithelium as well as, or instead of, reduced
Odontogenic cysts
enamel epithelium.
These are derived from residues of odontogenic epithe- As developmental jaw cysts are usually symptomless,
lium which otherwise gradually involute following secondary inflammatory changes often provoke initial

3. 88 CURRENTDIAGNOSTICPATHOLOGY
(A) (A)
(B) (B)
Fig. 3--A dentigerous cyst on a lower third molar tooth. (A) Fig. 4--Part of an odontogenic keratocyst which has formed
The cyst wall, attached at the enamel-cementum junction, alongside an unerupted tooth. (A) The white, folded lining
has been partially removed after fixation to reveal the reveals the presence of keratinising epithelium. Proximity
crown of the tooth. (B) Part of the vascular fibrous wall of a to a tooth is an incidental but not uncommon feature and
dentigerous cyst lined by non-keratinised stratified on a radiograph may simulate a dentigerous relationship.
squamous epithelium which shows a zone of mucous (B) Characteristic histological appearance of an
metaplasia. Such an appearance is characteristic in the odontogenic keratocyst epithelium: uniform thickness and
absence of inflammation. H&E. with a flat basal surface, elongate basal cells, a thin prickle
cell zone and corrugated parakeratin surface layer. The
fibrous wall is usually thin, delicate and vascular. H&E.
presentation and a high proportion of surgical specimens
of dentigerous cysts show lymphoplasmacytic infiltrates folded inner surface (Fig. 4A) following discharge of
in the wall and neutrophils in the epithelial lining. Accu- stacked keratin, as with an epidermoid cyst. In most
mulations of cholesterol clefts, foreign body giant cells cases, there should be little difficulty in establishing the
and haemosiderin-laden macrophages may greatly en- diagnosis histologically. Typically, the wall is thin and
large the wall and locally herniate into the cyst lumen. rarely removed intact. It is lined by uniform, para-
Thus, at cut-up, disrupted cysts may glisten with keratinised epithelium, some 10-12 cells thick, with a
discharging semi-fluid contents which are rich in flat basal surface (Fig. 4B). Key features are a narrow,
cholesterol. folded (corrugated) zone of keratin, prickle cells which
retain their long axes at right angles to the basement
membrane until close to the keratinised layer and elon-
Odontogenic keratocyst (primordial cyst)
gate, often palisaded, basal cells which show reversed
More has been written in recent years on the polarity in at least some areas. It was established many
odontogenic keratocyst than on any other jaw cyst. years ago that keratocysts show a higher frequency
Radiographically it has a multilocular, or apparently of mitoses than is found in other odontogenic cysts. 15
multilocular, appearance and is sometimes multiple, Mitotic figures may be found in both basal and parabasal
especially when it represents a manifestation of the layers. A study using PCNA as a marker of cell prolif-
naevoid basal cell carcinoma syndrome (Gorlin's syn- eration has shown higher indices for keratocysts than for
drome). Rather than expanding the jaw, the cyst tends other odontogenic cysts. 16 Odontogenic keratocysts have
to grow mesiodistally at the expense of the medullary a higher recurrence rate too, due in part to their physical
bone and extends between the roots of the teeth. fragility leading to disruption during removal, the
Macroscopically, the opened cyst reveals a white, epithelium separating easily from the fibrous wall. A

4. CYSTS AND CYSTICLESIONSOF THE JAWS 89
further possible reason is the presence of daughter cysts diagnosis in such cases, especially if the biopsy sample
in the wall which may remain after cyst enucleation. is small.
Differences in proliferation rates and in the frequency
of basal epithelial" cell budding between solitary, multi-
Lateral periodontal, botryoid, and glandular
ple and recurrent odontogenic keratocysts and those
odontogenic cysts
associated with naevoid basal cell carcinoma syndrome
have been the subject of a number of recent studies. 17 The lateral periodontal cyst is usually unilocular and lies
Significantly higher rates of mitosis occur in keratocysts alongside a vital tooth and therefore, like the radicular
in patients with Gorlin's syndrome. Satellite cysts have cyst, is presumed to originate from cell rests of Malassez
been detected in about 50% of syndrome patients and in in the periodontal ligament or possibly from part of
the walls of 25% of multiple or recurrent cysts whereas the developing follicle, z~ The stimulus to its formation is
they are found in less than 10% of solitary keratocysts. unknown, and it is usually detected as a symptomless
In practical terms, the possible diagnosis of naevoid radiolucency on routine radiography. Its epithelial lining
basal cell carcinoma syndrome should be investigated is about 2-6 cells thick, non-keratinised, stratified
for all patients with odontogenic keratocysts. The syn- squamous and with a flat basal surface. There may be
drome is an autosomal dominant condition with numer- a narrow zone of subepithelial hyalinisation, a feature
ous defects, many involving the axial skeleton. occasionally encountered in other odontogenic cysts and
It is important not to diagnose as a keratocyst every neoplasms. The fibrous wall is usually uninflamed,
odontogenic cyst which shows some keratinisation. Parts cellular and delicate, lacking daughter cysts. A charac-
of (probably) long-standing dentigerous or radicular teristic feature is the presence of periodic, plaqueqike
cysts may show ortho- or parakeratinisation but without thickenings in the epithelium (unrelated to inflamma-
the other features of odontogenic keratocysts. Also, soft tion) which may bulge into the cyst lumen or wall or
tissue removed together with impacted, partially erupted both (Fig. 6). These contain glycogen and may be
third molar teeth may include some keratinised gingival composed predominantly of clear cells but there is no
mucosa which may unwittingly be mistaken for kera- evidence that they represent centres of proliferation.
tocyst wall. It is of interest that, whilst all odontogenic Indeed, mitotic figures, epithelial budding and daughter
keratocysts keratinise, only a minority are orthokera- cyst formation are unusual in the lateral periodontal cyst.
tinised; moreover, these recur less frequently than A proportion of cysts which radiographically suggest
parakeratinising cysts. 18,19 a diagnosis of lateral periodontal cyst turn out to be
Although inflammatory infiltrates in odontogenic odontogenic keratocysts on histological examination,
keratocysts are usually well-localised and mild, diagnos- despite their unilocular profile.
tic problems may result from an ~xtensive inflammatory Botryoid and glandular odontogenic cysts are rare
infiltrate which suppresses keratinisation (Fig. 5). This entities with features in common with each other and
could give rise to misdiagnosis of a dentigerous or re- with the lateral periodontal cyst. The former is so called
sidual cyst with the consequence that, in the absence because the low magnification appearance or macro-
of follow-up, the patient may develop a recurrence scopic cut surface sometimes resembles a bunch of
which is unrecognised until well advanced. If, in a simi- grapes. Radiographically, most have been multilocular
lar context, the basal cells are markedly columnar the and located in the mandible. In their more detailed fea-
keratocyst might be misdiagnosed as an ameloblastoma, tures, botryoid cysts resemble lateral periodontal cysts,
particularly since the radiographic appearance of these the thin, non-keratinised epithelial lining with thickened
two lesions are sinfilar. One should be wary of over- plaques being a consistent feature. A number of recent
4~
Fig. 5 - - A keratocyst which has become secondarily Fig, 6--Wall of a lateral periodontal cyst with a Iocalised
inflamed. Note the loss of keratinisation in the zone thickening of the uniform, non-keratinising epithelium.
showing an arcading pattern of epithelial hyperplasia. If the Several such thickenings may be encountered in a given
biopsy is small or inflammatory change extensive, this may plane of section. H&E.
lead to a mistaken diagnosis of an inflammatory cyst. H&E.

5. 90 CURRENTDIAGNOSTICPATHOLOGY
publications point to a high recurrence rate for this
multicystic lesion.
Greater difficulty attaches to the status of the glandular
(sialo- or mucoepidermoid-) odontogenic cyst. It is sur-
prising that this cyst has been recognised only recently
as a distinct entity 21,22 and less than 20 cases have been
reported in the world literature. It has an appearance of
multilocularity on radiographic examination. Its histo-
logical features include multiple thickened epithelial
plaques, like those of the lateral periodontal cyst, and
multicystic growth, like the botryoid cyst. Intriguing
additional features are present in the epithelium: papil-
lary 'outgrowths' into the cyst lumen with apocrine-like
'decapitation' secretion of surface cells, ductal struc- Fig. 8--Radicular cyst: a frequent presentation with a
tures, mucin-producing goblet cells and occasionally dense, mixed inflammatory infiltrate adjacent to variably
acini (Fig. 7). The nomenclature for this cyst has not yet hyperplastic, non-keratinised epithelim. The upper part of
the field shows part of the wall apparently devoid of
been established and interpretations of the histological epithelium, also a common finding. H&E.
features range widely. Mucous metaplasia may be
present in the lining of any odontogenic cyst and to some
commentators, the glandular odontogenic cyst is an ex-
pattern of hyperplasia (Fig. 5) can be so striking that the
treme example of this change. An opposing view is that
unwary may suspect the presence of an ameloblastoma. 23
the lesion is in fact a low-grade central mucoepidermoid
It is essential that the condition of the related tooth be
carcinoma. When more cases become available for study
known for the correct diagnosis to be made: the histo-
and when a wider range of markers of odontogenic
logical features of a radicular cyst may be identical
epithelium have been developed, the histogenesis of this
to those of a secondarily inflamed dentigerous cyst.
group of cysts should become clearer.
Similarly, a long-standing radicular cyst may come to
resemble a developmental cyst when the inflammatory
Inflammatory odontogenic cysts infiltrate fades. A cyst which forms alongside a non-vital
tooth is termed a lateral radicular cyst and one which is
Radicular cyst
retained following removal of the offending tooth or root
By far the most common jaw cyst is the radicular cyst, is referred to as a residual cyst, the histological features
an odontogenic cyst which forms from epithelial rests of being identical to those just described.
Malassez in the periodontal ligament consequent upon
activation from the products of necrotic dental pulp in an
Paradental cyst
adjacent tooth. The wall is relatively thick and usually
contains a dense inflammatory infiltrate towards the The paradental cyst is an inflammatory cyst which lies
inner aspect, consisting of plasma cells and lymphocytes. on the disto-buccal aspect of fully or partially erupted
Neutrophils tend to accumulate in the epithelium which third molar teeth, near the bifurcation of the roots
is of non-keratinised, stratified squamous type and varies (Fig. 9). There is a male preponderance, a history of
greatly in thickness (Fig. 8). Sometimes the arcading pericoronitis is common and sometimes a predisposing
Fig. 7--Parts of two Iocules of a glandular (sialo-) Fig. 9--A paradental cyst attached to the enamel-cementum
odontogenic cyst with thickened epithelial plaques, similar junction of a lower molar tooth on the disto-buccal aspect.
to those found in lateral periodontal and botryoid cysts but Although slightly disrupted, it lies alongside the tooth and
also showing ductal structure, and extensive mucus- does not enclose the crown.
secreting cells. H&E.

6. CYSTS AND CYSTICLESIONSOF THE JAWS 91
factor is an extension of enamel down to where the roots Differential diagnosis should include other odonto-
separate and a bilateral presentation is not u n u s u a l . 24 The genic carcinomas: primary intra-osseous carcinomas,
associated tooth is therefore usually vital and such cysts which are thought to arise from residues of odontogenic
are often removed still attached after extraction of the epithelium in the jaws, and malignant variants of
erupting or partially erupted tooth due to impaction. ameloblastoma and other odontogenic tumours. Central
Whether the source of epithelium is the reduced enamel mucoepidermoid carcinomas, in which the epidermoid
epithelium, periodontal pocket epithelium or cell rests component may predominate, should also be considered.
of Malassez, the aetiological mechanism appears to be Any of these malignancies may be cystic, at least in
epithelial activation by inflammatory infiltrate which is part. The mandible is also a well-recognised site for car-
induced by bacterial plaque. cinomas metastatic to the jaws from such sites as lung,
A related cyst, the mandibular infected buccal cyst, breast, prostate, thyroid and kidney which may simulate
has a similar association with first or second lower per- cysts radiographically.
manent molar teeth 25 but in younger patients than the Dysplastic change may be encountered in cyst epithe-
paradental cyst. As Shear 2 argues, the two entities are lia and levels should be checked carefully for evidence
probably related but are worth while recognising as of frank invasion. This is particularly the case in those
distinct for reasons of management. odontogenic keratocysts which show basal budding
Both these cysts have the same histological appear- (Fig. 11) and epithelial islands, since the presence of
ance as the radicular cyst: hyperplastic, non-cornified dysplasia may give the impression of a wide field of
epithelium lining a fibrous wall containing a dense, invasion.
mixed inflammatory infiltrate. Clinical information is
therefore essential for an accurate diagnosis.
AmelobIastoma and its unicystic variants
Ameloblastomas are the most common odontogenic neo-
Malignant transformation in jaw cysts
plasms. They present usually in the mandibular third
Although rare, malignant transformation does occur in molar region and least often in the anterior maxilla.
odontogenic cysts, about 60 cases having been reported Their peak age prevalence is in the 4th or 5th decade.
in the world literature. Malignant transformation appears Histological criteria for their diagnosis were set out by
to arise most frequently in residual cysts, reported cases Vickers and Gorlin. 27 The epithelial cells comprise two
equalling those of dentigerous cysts and odontogenic distinct populations. Firstly, peripheral, or basal, cells
keratocysts combined; 80% of such malignancies occur which are columnar and often markedly elongate and
in the mandible (Fig. l()). 2r Not surprisingly, the age at showing reversed polarity, with the nucleus occupying
presentation tends to be greater than that of patients with the part of the cell away fi-om the basement membrane;
benign cysts; the 6th or 7th decade rather than the 4th or this layer thus resembles the pre-ametoblast of the devel-
5th. As far as can be assessed with such small numbers oping tooth germ. The second population consists of
of cases, the prognosis appears to be better than that of polyhedral suprabasal cells with fewer intercellular con-
mucosal carcinomas which infiltrate the .jaws, and that tacts than conventional prickle cells; this is the stellate
of primary intra-osseous carcinomas, nodal metastases reticulum-like layer, similar to the stellate reticulum of
being less common. This difference in prognosis might the bell stage in the developing tooth. Two principal
be expected when the carcinoma is removed while being arrangements of epithelium are recognised, follicular
retained within the confines of the fibrous cyst wall. (Fig. 12A) and plexiform (Fig. 12B), although there is
Fig. 10--Squamous cell carcinoma which has arisen in an Fig. 11--Odotogenic keratocyst showing extensive basal
odontogenic keratocyst. This mandibular t u m o u r was more budding together with bulbous rete processes and some
solid than cystic but dysplastic keratocyst lining is still cell disorganisation but minimal cytological features of
evident associated with islands of well-differentiated malignancy. However, the presence of these features
carcinoma. A dense lymphocytic response is also present. increase the likelihood of recurrence. H&E.
H&E.

7. 92 CURRENTDIAGNOSTICPATHOLOGY
be confused with an odontogenic keratocyst. 28 An addi-
tional but rare feature of ameloblastomas is the inclusion
of eosinophilic granular cells whose origin is obscure but
which are befieved to arise in the epithelial compartment.
Other variants of ameloblastoma may also be pre-
dominantly cystic:
9 Desmoplastic, in which the stroma is more densely
fibrous.
9 Basal cell, in which basaloid cells predominate.
9 Papilliferous keratoameloblastoma, a rare type in which
cystic spaces may be filled with desquamated, kerati-
nising squames.
Some ameloblastomas are characteristically unilocular
(A)
on radiographs and prove to be unicystic (Fig. 13), and
sometimes in a dentigerous relation to a tooth, when
examined macroscopically. They also tend to present in
younger patients than do conventional ameloblastomas.
Levels should be taken through the excision specimen
to investigate the presence of a conventional amelo-
blastoma. Sometimes part of the lining expands into a
plexiform pattern of ameloblastoma. On occasion, strict
criteria for ameloblastoma can be hard to establish and
the diagnosis has to take account of the clinical presenta-
tion as well as 'suggestive' features in the epithelial lin-
ing. Unicystic ameloblastomas are generally considered
to have a lower recurrence rate than their conventional
counterparts. This is true of those with a continuous
epithelial lining and those with ameloblastomatous mural
(B) nodules which invaginate the lumen. They may be
Fig. 12--Examples of cyst formation in conventional treated successfully by careful enucleation, but when
ameloblastomas. (A) Follicular ameloblastomas with cystic
the wall is found to be infiltrated by islands of amelo-
change in the stellate reticulum component of the
neoplasm. The cystic area on the right is lined by cells blastomatous epithelium treatment should be as radical
showing 'acanthomatous' change. (B) Plexiform as for the conventional solid or multi-cystic types. 13
ameloblastomas with stromal cysts; surviving small blood
vessels indicate the location of the connective tissue
component. The lumen of the main cyst is shown at the top
of the figure and is composed of degenerate epithelial cells.
Calcifying odontogenic cyst
H&E.
This curious entity is usually classified with epithelial
odontogenic tumours since it is really a neoplasm which
sometimes may be as aggressive as an ameloblastoma.
no behavioural difference between the two. Although
usually slow growing and lacking in detectable mitoses,
both types tend to infiltrate the bone and to recur unless
removed by local resection. The follicular form consists
of round or irregular islands of tumour, the stroma being
composed of vascular, cellular fibrous tissue. As its de-
scriptive name suggests, in the plexiform ameloblastoma
the epithelial component takes the form of interlacing
strands which appear to entrap the stroma. Cystic change
is common in both types, microcysts forming in the
epithelial masses and stromal cysts in the connective
tissue. As the ameloblastoma enlarges, the cysts coalesce
and may form one or more cystic cavities containing
straw-coloured fluid. Biopsy of the stretched wall of
such a tumour may lead to the misdiagnosis of a non-
neoplastic cyst. Fortunately, the solid or invaginated Fig. 13--Unicystic ameloblastoma. This lesion shows few
areas are likely to contain more representative amelo- histological hallmarks of an ameloblastoma, Basal
blastoma. Another conmaon feature of ameloblastomas is epithelial cells palisaded in places but with little evidence of
the reversed polarity characteristic of ameloblasts and
squamous metaplasia ('acanthomatous change') which stellate reticulum cells are poorly developed. Epithelium in
only rarely consists of true keratinisation when it may this field has a somewhat plexiform arrangement. H&E.

8. CYSTS AND CYSTIC LESIONS OF THE JAWS 93
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