Case Scenario
A 45-year-old African man presents in the dental accident and emergency department with an enlarged jaw.You need to make a diagnosis and decide on treatment.
Table of Contents
Complaint
The patient’s main complaint is that his lower back teeth on the right side are loose and that his jaw on the right feels enlarged.
History of Complaint
The patient has been aware of his teeth slowly becoming looser over the previous 6 months. They seem to be ‘moving’ and are now at a different height from his front teeth, making eating difficult. He is also concerned that his jaw is enlarged and that there seems to be reduced space for his tongue. He has recently had the lower second molar on the right extracted. It was also loose, but extraction does not seem to have cured the swelling. Although not in pain, he has finally decided to seek treatment.Medical History
He is otherwise fit and healthy.
Examination
Extraoral Examination
He is a fit-looking man with no obvious facial asymmetry but has a slight fullness of the mandible on the right. Palpation reveals a smooth, rounded, bony hard enlargement on the buccal and lingual aspects. Deep cervical lymph nodes are palpable on the right side. They are only slightly enlarged, soft, not tender and freely mobile.
Intraoral Examination
There is a large swelling of the right posterior mandible visible in the buccal sulcus, its anterior margin is relatively well defined and level with the first premolar. The lingual aspect is not visible, but the tongue appears displaced upwards and medially, suggesting significant lingual expansion. The mucosa over theswelling is of normal colour, without evidence of inflammation or infection. There are two relatively small amalgams in the lower right molar and the second premolar. If you could examine the patient, you would find that all his upper right posterior teeth have been extracted and that the lower molar and premolars are 2–3 mm above the height of the occlusal plane. These teeth are grade 3 mobile but still are vital.
What are the Red Spots On the Patient’s Tongue?
Fungiform papillae. They appear more prominent when the tongue is furred, as in this case, when the diet is not very abrasive.
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On the Basis of What You Know So Far, What Types of Condition Would You Consider is Present?The history suggests a relatively slow-growing lesion, which is, therefore, likely to be benign. Although this is not a definitive relationship, there are no specific features suggesting malignancy, such as perforation of the cortex, soft tissue mass, ulceration of the mucosa, numbness of the lip or devitalization of teeth. The character of the lymph node enlargement does not suggest malignancy. The commonest jaw lesions that cause expansion are odontogenic cysts. The commonest odontogenic cysts are the radicular (apical inflammatory) cyst, dentigerous cyst and odontogenic keratocyst. If this is a radicular cyst, it could have arisen from the first molar, although the occlusal amalgam is relatively small and there seems to be no reason to suspect that the tooth is not vital. A residual radicular cyst arising on the extracted second or third molar would be a possibility. A dentigerous cyst could be the cause if the third molar is unerupted. The possibility of an odontogenic keratocyst seems unlikely because these cysts do not normally cause much expansion. An odontogenic tumour is a possible cause, and an ameloblastoma would be the most likely one because it is the commonest and arises most frequently at this site and in this age group. There is a higher prevalence in Africans than in other racial groups. An ameloblastoma is much more likely than an odontogenic cyst to displace teeth and make them grossly mobile. A giant cell granuloma and numerous other lesions are possibilities but are all less likely.
Radiographic Views
| Radiographic View | Reason |
|---|---|
| Panoramic or oblique lateral radiograph |
To show the lesion from the lateral aspect. The oblique lateralwould provide the better resolution but might not cover theanterior extent of this large lesion. The panoramic radiograph would provide a useful survey of the rest of the jaws but only that part of this expansile lesion in the line of the arch will bein focus. An oblique lateral view was taken. |
| A postero-anterior (PA)view of the jaws |
To show the extent of mediolateral expansion of the posterior body, angle or ramus. |
| A lower true (90˚) occlusal view |
To show lingual expansion, which will not be visible in the PA view of the jaws because of superimposition of the anterior body of the mandible. |
| A periapical view of the lower right second premolar and the first molar |
To assess bone support and possible root resorption. |
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| Postero-Anterior View |
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| Obloque Lateral View |
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| Lower True Occlusal View |
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| Periapical View of lower right 6 |
Why Do the Roots of the First Molar and the Second Premolar Appear To Be So Resorbed in the Periapical View When the Oblique Lateral View Shows Minimal Root Resorption?
The teeth are foreshortened in the periapical view because they lie at an angle to the image receptor. This image has been taken by using the bisected angle technique and several factors contribute to the distortion:
- the teeth have been displaced by the lesion, so their crowns lie more lingually, and the roots more buccally;
- The lingual expansion of the jaw makes image receptor placement difficult, so it has had to be severely tilted away from the root apices;
- There was failure to take account of these two factors when positioning and angling the x-ray tubehead.
Radiographic Differential Diagnosis
What is Your Principal Differential Diagnosis?
- Ameloblastoma
- Giant cell lesion
Ameloblastoma classically produces an expanding multi-locular radiolucency at the angle of the mandible. As noted above, it most commonly presents at the age of this patient and is commoner in his racial group. The radiographs show the typical multi-locular radiolucency, containing several large cystic spaces separated by bony septa, and the root resorption, tooth displacement and marked expansion are
all consistent with an ameloblastoma of this size.
Several lesions remain possible but are less likely on the basis of either their features or their relative rarity.
Rarer odontogenic tumours,
including particularly odontogenic fibroma and myxoma. These similar benign connective tissue odontogenic tumours are often indis tinguishable from one another radiographically. Odontogenic myxoma is commoner than fibroma, but both are relegated to the position of unlikely diagnoses on the basis of their relative rarity and the younger age group affected. Both usually cause a unilocular or apparently multilocular expansive radiolucency at the angle of the mandible and displace adjacent teeth or sometimes loosen or resorb them. A characteristic, although inconsistent, feature in myxoma is that the internal dividing septa are usually fine and arranged at right angles to one another, in a pattern sometimes said to resemble the letters ‘X’ and ‘Y’ or the strings of a tennis racket. In myxoma, septa can also show the honeycomb pattern described in giant cell granuloma.
Odontogenic keratocyst. This is unlikely to be the cause of this lesion, but in view of its relative frequency, it might still be included at the end of the differential diagnosis. It should be included because it can cause a large multi-locular radiolucency at the angle of the mandible in adults, usually slightly younger than this patient. However, the growth pattern of an odontogenic keratocyst is quite different from that of the present lesion. Odontogenic keratocysts usually extend a considerable distance into the body and/or ramus before causing significant expansion. Even when expansion is evident, it is usually a broad-based enlargement rather than a localized expansion. Adjacent teeth are rarely resorbed or displaced.
What Lesions Have You Discounted, and Why?
Dentigerous cyst is a common cause of large radiolucent lesions at the angle of the mandible. However, the present lesion is not unilocular and does not contain an unerupted tooth. Similarly, the radicular cyst is unilocular but associated with a nonvital tooth.
Malignant neoplasms, either primary or metastatic. As noted above, the clinical features do not suggest malignancy, and the radiographs show an apparently benign, well-defined, slowly enlarging lesion.
Further Investigations
Is a Biopsy Required?
Yes. If the lesion is an ameloblastoma, the treatment will be excision, whereas if it is a giant cell granuloma, curettage will be sufficient. A definitive diagnosis based on biopsy analysis is required to plan treatment.
Would Aspiration Biopsy Be Helpful?
No. If an odontogenic keratocyst were suspected, this diagnosis might be confirmed by aspirating keratin. It would also be helpful in determining whether the lesion is solid or cystic. It would not be particularly helpful in the diagnosis of ameloblastoma.
What Precautions Would You Take At Biopsy?
An attempt should be made to obtain a sample of the solid lesion. If this is an ameloblastoma and an expanded area of the jaw is selected for biopsy, it will almost certainly overlie a cyst in the neoplasm. A large part of many ameloblastomas is cyst space, and the stretched cyst lining is not always sufficiently characteristic histologically to make the diagnosis. If the lesion proves to be cystic on biopsy analysis, the surgeon should open up the cavity and explore it to identify solid tumour for sampling.
The surgical access must be carefully closed on bone to ensure that healing is uneventful and infection does not develop in the cyst spaces. The expanded areas may be covered by only a thin layer of eggshell-like periosteal bone. Once this is opened, it may be difficult to replace the margin of a mucoperiosteal flap back onto solid bone.
Diagnosis
The Final Diagnosis is Ameloblastoma, Conventional Type. Does the Type of Ameloblastoma Matter?Yes, it is important for treatment planning. There are several different types of ameloblastoma, and not all exhibit extension into the surrounding medullary cavity. The characteristics of the main types are shown in
Main Type of Ameloblastoma
| Type | Features | Permeates Surrounding Bone? |
|---|---|---|
| Conventional
ameloblastoma | The commonest type, previously called solid/multicystic ameloblastoma. Usually contains multiple cysts and has a multilocular radiographic appearance. Plexiform, follicular and mixed histological variants exist but have no bearing on behaviour or treatment. Desmoplastic ameloblastoma used to be considered a separate type but is now grouped with conventional ameloblastoma because intermediate conventional and desmoplastic types exist. However, it is worth being aware of this pattern because radiographically, it forms a fine honeycomb radiolucency that may resemble a fibro-osseous lesion with a margin that is difficult to define. No large cysts are present, and histologically, it comprises sparse islands of ameloblastoma dispersed in dense fibrous tissue. Unusually, this pattern is as frequent in the maxilla as in the mandible, and most cases exhibit spread into adjacent medullary spaces. | Yes, in a quarter or less of cases |
| Unicystic
ameloblastoma | An ameloblastoma with only one cyst cavity and no separate islands of tumour, or just a few limited to the inner part of the fibrous wall. Presents radiographically as a cyst, sometimes in a dentigerous relationship. Can only be diagnosed definitively as a unicystic ameloblastoma by performing a complete histological examination after treatment. | No |
| Peripheral or
extraosseous ameloblastoma | An ameloblastoma that develops as a soft tissue nodule outside bone, usually on the gingiva. Usually detected when small and readily excised. This variant is very rare. | No (the lesion is outside bone) |
Treatment
The ameloblastoma in this patient is classified as a benign neoplasm. However, it is locally infiltrative and, in some cases, permeates the medullary cavity around the main tumour margin. Ameloblastoma has to be excised with a 1 cm margin of normal bone and around any suspected perforations in the cortex to prevent recurrence. If ameloblastoma has escaped from bone, it may spread exten- sively in soft tissues and requires excision with an even larger margin. The lower border of the mandible may be intact and is sometimes left in place to avoid the need for full-thickness resection of the mandible and a bone graft. This carries a low risk of recurrence, but such recurrences are slow growing and may be dealt with conservatively after the main portion of the mandible has healed.However, multifocal or second recurrence requires resection. Conservative treatment is not appropriate in the maxilla, where even conventional treatment carries a risk of recurrence, and occasionally, recurrent ameloblastoma can extend to the base of the skull and be inoperable. In this case, the lesion is clearly extensive and multilocular, filling almost the whole ramus and posterior body. In a case such as this, definitive resection in one operation is much better for the patient. The fact that the ameloblastoma in this patient is of the follicular pattern is of no significance for treatment.