OMS Tumors

Question 1

What clues at initial manifestation may signify increased concern for a malignant versus benign odontogenic tumor?

Answer 1

Pain, paresthesia, trismus, and rapid onset of malocclusion

are associated with increased risk of malignancy.

Question 2

What are the important aspects of the history of a patient with a possible odontogenic mass?

Answer 2

Onset and duration/progression of the mass, complete
dental history including any previous surgical intervention,
erupted teeth, paresthesia, loose or displaced teeth,
malocclusion, pain or absence thereof, trauma, and
systemic symptoms

Question 3

What are the most common sites for odontogenic

tumors?

Answer 3

Mandibular molars and maxillary cuspids

Question 4

Name the different types of odontogenic malignancies.

Answer 4

Malignant ameloblastoma, ameloblastic carcinoma, primary
intraosseous squamous cell carcinoma, clear cell odonto-
genic carcinoma, malignant calcifying epithelial odonto-
genic tumors, odontogenic ghost cell carcinoma,
ameloblastic fibrosarcoma

Question 5

What are the most common sites of metastasis for

malignant odontogenic tumors?

Answer 5

Lungs are most common, followed by regional lymph

nodes.

Question 6

Describe the classification system for primary
intraosseous carcinomas of the jaw presented by
Elzay in 1982.

Answer 6

● Type I: Arising from exodontogenic cysts (e.g., squamous
cell carcinoma)
● Type II: Odontogenic carcinomas (e.g., ameloblastic
carcinoma)
● Type III: Arising de novo (e.g., squamous cell carcinoma)
● Type IV: Sarcomas (e.g., myoepithelial carcinoma)

Question 7

What is the recommended treatment for odontogenic malignancies?

Answer 7

Because of the extreme rarity of these cancers, no definitive
diagnostic algorithm has been developed. In general, wide
surgical excision is the treatment of choice.

Question 8

How should a biopsy be undertaken for suspected intraosseous odontogenic tumors?

Answer 8

Depending on patient tolerance and anticipated procedure,
anesthesia may be local only or any form of sedation or
general anesthesia. Typically, mucosal incision takes place in
an uninvolved area that can be easily closed. Aspiration is
advised to rule out vascular lesions, after which safe entrance through the bone is undertaken. Specimens should include any areas of radiologic variation to ensure adequate sampling. Excisional biopsy is appropriate for cysts that are small and do not appear malignant on
imaging. Incisional biopsy is warranted for larger lesions
concerning for malignancy as a precursor to more definitive resection.

Question 9

What aspects of an odontogenic tumor are most important to management decision-making?

Answer 9

Although histology is useful in distinguishing these lesions from one another, it is less important in terms of
management. Intervention should be dictated by the
behavior of the lesion itself, with particular attention given to the extent of local invasion, disruption of
nearby anatomical structures, and destructiveness of the
lesion.

Question 10

What are common risk factors for malignancies

originating from odontogenic cysts and tumors?

Answer 10

Many odontogenic carcinomas are found in sites of prior
cysts, (more commonly than odontogenic tumors), and many are noted in edentulous sites on the mandible/maxilla. Dentigerous cysts are the source of transformation
in as many as 25% of cases.

Question 11

Describe the clinical presentation of ameloblastoma.

Answer 11

Ameloblastomas manifest in a wide range of ages, with
peak in the third and fourth decades of life. Patients have a
slow-growing, painless bony mass, usually in the posterior
mandible, although both jaws may be affected. The tumor
is locally invasive, and malignant transformation is rarely noted. The tumor may recur with inadequate resection,
especially the solid variant. Radiology is notable for
expansive radiolucent lesions that can be unilocular or
multilocular and have a characteristic “soap bubble” or
“honeycombed” appearance.

Question 12

What is the most common odontogenic tumor?

Answer 12

Ameloblastoma

Question 13

Compare and contrast ameloblastoma with calcifying epithelial odontogenic tumors (CEOT; Pindborg tumors).

Answer 13

Both are highly infiltrative and destructive epithelial-derived tumors, presenting as a radiolucent, slow-growing, and
painless mass. CEOTs are much less common than ameloblastoma and histopathologically show evidence of
scattered calcification with concentric rings known as Liesegang rings. Unlike ameloblastoma, CEOT has large areas of eosinophilic tissue that stain positive for amyloid with Congo red.

Question 14

What is the difference between malignant ameloblastoma and ameloblastic carcinoma?

Answer 14

Malignant ameloblastoma is characterized by benign-
appearing histology but distant metastasis. Ameloblastic carcinoma has the basic ameloblastoma pattern but is
dedifferentiated with atypia, hypercellularity, and mitoses, with or without regional or distant metastasis.

Question 15

How can malignant ameloblastoma be distinguished from ameloblastoma or ameloblastic carcinoma?

Answer 15

Malignant ameloblastoma is identified by the presence of metastasis, most often to the lungs. Local invasion is frequently aggressive, similar to ameloblastoma. Histology is notable for similar appearance to the primary ameloblastoma, but the hallmarks of malignancy (invasion of surrounding structures, frequent mitotic figures) are seen in ameloblastic
carcinoma. Resection of the tumor is recommended in all
cases, and although controversial, adjuvant treatment with radiation or chemotherapy is sometimes warranted.

Question 16

Why is the adenomatoid odontogenic tumor

known as the “two-thirds tumor”?

Answer 16

Adenomatoid odontogenic tumors occur in the second and
third decades of life, two-thirds of the time in females. Two-thirds are associated with an unerupted/impacted tooth (usually a cuspid), two-thirds of which are a canine, two-thirds of the time in the maxilla.

Question 17

What are mesenchymal odontogenic neoplasms (no

epithelial component)?

Answer 17

Odontogenic myxoma, cementoblastoma, central and peripheral odontogenic fibromas

Question 18

Compare and contrast odontogenic myxoma with ameloblastoma.

Answer 18

Both tumors are similar in terms of clinical and radiographic
presentation in that both are slow growing and usually
asymptomatic, both can be quite destructive (displacement/
absorption of tooth roots), both manifest preferentially in the
posterior mandible, and both do not impact sensation.
However, myxomas frequently appear earlier (in the third
decade vs. the fourth for ameloblastoma), and ameloblastomas
originate from the epithelium, whereas myxomas are mesen-
chymal. Both demand excision with a wide margin of tissue.

Question 19

What distinguishes a cementoma from other

benign odontogenic tumors?

Answer 19

Cementoma is an outdated term used to indicate a tumor
producing cementum (a calcified substance covering the
tooth root). There are three different entities previously associated with the term cementoma: periapical cementoosseous dysplasia, cementoblastoma, and ossifying fibroma.

Question 20

What clinical features define ameloblastic

fibroma?

Answer 20

Ameloblastic fibromas are found primarily in younger patients (seldom over age 40 years), usually in the posterior mandible. They present as a painless, radiolucent mass that often overlies an unerupted tooth.

Question 21

What is the natural history of most osteomas of

the jaws?

Answer 21

Osteomas are benign hamartomatous bony proliferations,
and are made up of compact bone found either on the
surface of the jaws in the case of periosteal osteoma or
within the bone in endosteal osteomas. An association
between multiple osteomas and familial adenomatous
polyposis is described in Gardner syndrome.

Question 22

What is the cause of mandibular tori?

Answer 22

It is probably multifactorial, with a possible autosomal

dominant inheritance. They may also be a result of bone stress.

Question 23

What is the recommended treatment for torus

palatinus?

Answer 23

Observation, unless there is need for a denture, recurrent

traumatic ulceration, or a change in speech

Question 24

Describe the presentation and management of

central giant cell lesions.

Answer 24

Central giant cell tumors are benign, but locally aggressive
lesions affecting the long bones can also occur in the jaws,
particularly the anterior mandible. The first through the third
decades are most common, and they manifest as an
asymptomatic, painless swelling, although pain or numbness
is occasionally noted. Curettage is typically an effective treatment, although recurrence should prompt wider resection. Medical interventions have also been described as having some success, notably steroids, interferon, and calcitonin. Bisphosphonate therapy has also been advocated.

Question 25

Why is the name aneurysmal bone cyst a misnomer?

Answer 25

Aneurysmal bone cysts are not cysts at all because they lack
any endothelial or epithelial lining. Rather, they are
expansile osteolytic bone lesions that fill with blood. They
are thought to be a variant of giant cell tumor or develop
within these tumors.

Question 26

Describe the natural history of ossifying fibroma.

Answer 26

Ossifying fibromas are benign growths that stem from mesenchymal cells. They occur most often in the tooth-bearing
jaws and are more common in women. They can become quite large but respond to enucleation and curettage if detected early
(under 2 to 3 cm). Larger masses require resection, although a
large margin is unnecessary as they are unlikely to recur. They progress from radiolucent to mixed to radio-opaque.

Question 27

What is the cause of fibrous dysplasia?

Answer 27

Fibrous dysplasia is a genetic condition in which medullary
bone is replaced by immature bone and fibrous tissue. It
most commonly affects one bone (monostotic—90%) but
can be seen in multiple bones (polyostotic), most notably in
McCune-Albright syndrome.

Question 28

Describe the findings in McCune-Albright syndrome.

Answer 28

Patients with McCune-Albright syndrome commonly have
at least two of the following: hyperfunction of endocrine glands (often manifest with precocious puberty), cafe-au-lait spots (unilateral), and polyostotic fibrous dysplasia (which can manifest in the mandible/maxilla, among many
other locations).

Question 29

What pathologic change gives rise to the characteristic mandibular swelling in cherubism?

Answer 29

In cherubism, bone in the mandible (and occasionally maxilla) is gradually replaced by multilocular cysts com-
prising vascular fibrous tissue with multinucleated giant cells. It is symmetric and usually self-limited and will frequently regress with the onset of puberty, often with
total involution. Surgery is rarely warranted to treat
ophthalmologic or orthodontic complications. Inheritance is autosomal dominant, with near complete penetrance in males.

Question 30

Describe the pathophysiology of osteitis deformans (Paget disease), and how is diagnosis made?

Answer 30

Paget disease arises from increased bone formation and resorption. Dense, sclerotic pagetoid bone will be disor-
ganized and weak and may bend or fracture in earlier stages. Diagnosis is often delayed by the fact that patients are asymptomatic. Eventually, deep bone pain or charac-
teristic enlargement of the skull, bowing of the legs, hearing loss, or fractures may bring the disease to the attention of the patient or clinician. Diagnosis is confirmed by radiographs, which demonstrate polyostotic or mosaicpatterned bone. Elevated serum alkaline phosphatase and urine hydroxyproline from increased bone turnover are also
useful.