A Potpourri of Head and Neck Pathology
Moderators: Dr. Leon Barnes and Dr. Antonio Cardesa
Section 6 -
Cysts and Cyst-like Tumors of the Jaws
Pieter J. Slootweg
Radboud University Medical Center
Nijmegen, The Netherlands
The jaws contain a variety of neoplastic and non-neoplastic cystic lesions. Generally, they are
classified as shown in the Table.
Table. Cystic lesions of the jaws
Radicular cysts are located at the root tips of teeth. They arise from the
epithelial rests of Malassez and are the cysts most frequently seen. They are lined by nonkeratinizing
squamous epithelium that may be thin and atrophic or show elongated rete processes. Within the cyst
epithelium, hyaline bodies of various size and shape may be present, the so-called Rushton bodies.
Occasionally, the lining squamous cells are admixed with mucous cells or ciliated cells. Sometimes, the
histologic pattern of the radicular cyst is complicated by extensive intramural proliferation of squamous
epithelial nests of varying size, thus mimicking a squamous odontogenic tumour. When a radicular cyst is
retained in the jaws after removal of the associated tooth, the lesion is called residual cyst .
|A. Odontogenic cysts - inflammatory ||Radicular cyst|
| ||Residual cyst|
| ||Paradental cyst|
|B. Odontogenic cysts - developmental ||Dentigerous cyst|
| ||Lateral periodontal cyst|
| ||Botryoid odontogenic cyst|
| ||Glandular odontogenic cyst|
|C. Non - odontogenic cysts ||Nasopalatine duct cyst|
| ||Nasolabial cyst|
| ||Surgical ciliated cyst|
|D. Cystic odontogenic tumours ||Ameloblastoma (unicystic)|
| ||Keratocystic odontogenic tumour (keratocyst)|
| ||Calcifying cystic odontogenic tumour|
| ||Adenomatoid odontogenic tumour|
|E. Pseudocysts, either neoplastic or non-neoplastic ||Focal bone marrow defect|
| ||Solitary bone cyst|
| ||Aneurysmal bone cyst|
| ||Ossifying fibroma (juvenile psammomatoid)|
The paradental cyst is located at the lateral side of the tooth at the
border between enamel and root cementum. This cyst is secondary to an inflammatory process in the
adjacent periodontal tissues that induces proliferation of neighbouring odontogenic epithelial rests,
similar to the pathogenesis of the radicular cyst.
A dentigerous cyst surrounds the crown of an unerupted tooth, mostly the
maxillary canine or the mandibular third molar tooth. The cyst wall has a thin epithelial lining that
may be only two to three cells thick. In case of inflammation, the epithelium becomes thicker and will
show features similar to the lining of a radicular cyst. Also, mucous producing cells as well as
ciliated cells may be observed. The cyst wall may also contain varying amounts of epithelial nests
representing remnants of the dental lamina.
Lateral periodontal cysts are derived from odontogenic epithelial remnants,
and occuring adjacent to the roots of vital teeth. They are lined by a thin, non-keratinizing squamous
or cuboidal epithelium with focal, plaque-like thickenings that consist of clear cells that may contain
glycogen. The botryoid odontogenic cyst represents a multilocular form of
the lateral periodontal cyst.
The glandular odontogenic cyst is characterized by an epithelial lining
with cuboidal or columnar cells both at the surface and lining crypts or cyst-like spaces within the
thickness of the epithelium. The lining epithelium is partly nonkeratinizing squamous with focal
thickenings similar to the plaques in the lateral periodontal cyst and the botryoid odontogenic cyst.
There may be a surface layer of eosinophilic cuboidal or columnar cells that can have cilia and may form
papillary projections. Some superficial cells show apocrine features. Also, mucus producing cells may
be present. In areas of thickened epithelium glandular spaces are formed. Moreover, the epithelial
cells may form whorls.
Nasopalatine duct cysts arise within the nasopalatine canal from epithelial
remnants of the nasopalatine duct. Radiologically, they present as radiolucent lesions situated between
the roots of both maxillary central incisor teeth. The cyst lining may be pseudostratified columnar
ciliated epithelium, stratified squamous epithelium, columnar or cuboidal epithelium and combinations of
these. As surgical treatment comprises emptying the nasopalatine canal, the specimen always includes the
artery and nerve that run in this anatomic structure. These are seen within the fibrous cyst wall and
form the most convincing diagnostic feature as the specific epithelial structures may be obscured by
Nasolabial cysts are located in the soft tissue just lateral to the nose at
the buccal aspect of the maxillary alveolar process and are thought to arise from the nasolacrimal duct.
Non-ciliated pseudostratified columnar epithelium with interspersed mucous cells form the epithelial
lining. These features may be lost through squamous metaplasia.
Surgical ciliated cysts arise from detached portions of the mucosa that
line the maxillary antrum that are buried within the maxillary bone. The cyst lining consists of
pseudostratified ciliated columnar epithelium with interspersed mucous cells.
The solitary bone cyst, also known as traumatic bone
cyst or simple bone cyst is confined to the mandibular body. It
consists merely of a fluid-filled cavity from which material for histologic examination may be difficult
to obtain as a soft tissue lining of the bony cavity may be entirely absent or very thin. If present, it
usually consists only of loose fibrovascular tissue, although it may also contain granulation tissue with
signs of previous haemorrhage such as cholesterol clefts and macrophages loaden with iron pigment.
The focal bone marrow defect represents an asymptomatic radiolucent lesion
of the jaws which contains normal hematopoietic and fatty bone marrow. It is also called osteoporotic bone marrow defect. Mostly, this
condition is seen at the angle of the mandible where it reveals its presence as a radiolucency with more
or less well-defined borders.
Unicystic ameloblastoma represents a cyst that
is lined by ameloblastomatous epithelium. This epithelium may proliferate to form intraluminal nodules
with the architecture of plexiform ameloblastoma. Downward proliferation of this epithelium may lead to
infiltration of the fibrous cyst wall by ameloblastoma nests. Sometimes, the cyst lining itself lacks
any features indicative of ameloblastoma, these being confined to intramural epithelial nests.
Inflammatory alterations may obscure the specific histologic details.
Adenomatoid odontogenic tumour consists of two different cell populations:
spindle shaped and columnar. The spindle shaped cells form whorled nodules that may contain droplets of
eosinophilic material. Thin epithelial strands may connect these nodules to each other. The columnar
cells line duct-like spaces with a lumen either empty or containing eosinophilic material and may form
curvilinear opposing rows with interposed eosinophilic material. In the stroma, there are large
aggregates of eosinophilic hyaline material. In some adenomatoid odontogenic tumours, areas of
eosinophilic cells with well-defined cell boundaries and prominent intercellular bridges similar to those
observed in the calcifying epithelial odontogenic tumour are seen. They do not influence the biologic
behaviour of this tumour and are considered to be part of its histologic spectrum.
Calcifying odontogenic cyst shows an epithelial lining similar to unicystic
ameloblastoma but in addition, there are intraepithelial eosinophilic ghost cells that may undergo
calcification. Ghost cell aggregates also may herniate through the basal lamina into the underlying
stroma where they evoke a giant cell reaction. In the fibrous stroma adjacent to the basal epithelial
cells, homogenous eosinophilic material resembling dentin may be found in varying amounts. Dentin-like
material and ghost cells together may lie intermingled. To this simple unicystic structure other
features may be added thus creating different subtypes with different names. The most recent WHO
classification proposes the diagnostic designations calcifying cystic odontogenic
tumour and dentinogenic ghost cell tumour to discern between the
cystic and the solid lesion.
Keratocystic odontogenic tumour (Odontogenic keratocyst) shows a thin
connective tissue wall lined by stratified squamous epithelium with a well defined basal layer of
palissading columnar or cuboidal cells and with a surface of a corrugated layer of parakeratin. The
underlying cyst wall may contain tiny daughter cysts and solid epithelial nests. When inflamed, the
typical histologic features are replaced by a non-keratinizing stratified epithelium exhibiting
spongiosis and elongated rete pegs supported by a connective tissue containing an mixed inflammatory
infiltrate. They also occur as part of the nevoid basal cell carcinoma syndrome or Marfan's syndrome.
Occasionally, intraosseous cysts are lined by orthokeratinized epithelium, thus having the appearance of
an epidermoid cyst. Such cysts are known as orthokeratinized odontogenic cyst. Their differentiation
from the keratocystic odontogenic tumour is clinically important as recurrence of the orthokeratinized
cysts is rare in contrast with the keratocystic odontogenic tumour.
Juvenile psammomatoid ossifying fibroma may be largely cystic in its gross
appearance. This subtype of ossifying fibroma has a fibroblastic stroma with small ossicles resembling
psammoma bodies, hence its name. The stroma varies in cellularity. The spherical or curved ossicles are
acellular or include sparsely distributed cells and may coalesce to form trabeculae. Some cases contain
basophilic concentrically lamellated particles as well as irregular thread-like or thorn-like calcified
strands in a hyalinized background. Trabeculae of woven bone as well as lamellar bone, pseudocystic
stromal degeneration and haemorrhages resulting in areas similar to an aneurysmal bone cyst,
multinucleate giant cells, and mitotic figures can also be observed.
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