Ameloblastoma

Case contributed by Prof Oliver Hennessy

Presentation

Jaw pain.

Patient Data

Age: 42
Gender: Male
Modality: X-ray

Large cystic lesion within the body of the left mandible extending from adjacent to the root of 33 to the mesial aspect of the 37. A single dental fragment is seen along the intervening mandibular alveolar bone. No internal sequestrum seen. No definite fracture on this single projection. No periapical lucencies seen to suggest dental abscess formation.

Temporomandibular joints are enlocated. Maxillary sinuses clear.

 

Modality: CT

There is a large expansile bony lesion of the left hemi-mandible noted, measuring. Cortical thinning is noted with no definite dehiscence. There is no knife edge resorption of the involved teeth roots. The lesion contains complex fluid with a HU of 23. There is no soft tissue component noted. The lesion involves the inferior alveolar canal. There is no suspicious local adenopathy. There is bilateral maxillary sinus disease.

CONCLUSION:

Expansile bony lesion involving the left hemi-mandible. The imaging features are not typical of an ameloblastoma. While there is involvement of the roots of the teeth, there is not knife edge resorption as described in ameloblastoma. The differential includes a aneurysmal bone cyst or giant cell reparative granuloma.

MRI correlation and biopsy is indicated.

PATHOLOGY 

CLINICAL NOTES: Cystic lesion L mandible - ?KCOT.

The lesion appeared unicystic both radiologically and at the time of surgery.

MACROSCOPIC DESCRIPTION:

"Left marsupialization plus tooth": The specimen comprises three teeth and fragments of tan soft tissue measuring in aggregate 25x25x3mm. All soft tissue is submitted for histological examination. P1. (MAS)

MICROSCOPIC DESCRIPTION: Sections show fragments of trabecular bone and adjacent fibrous tissue. Within the fibrous tissue there is an ameloblastoma comprising fragments of a peripherally pallisaded and focally basaloid appearing epithelial lining of columnar cells with hyperchromatic nuclei with focal areas demonstrating reverse polarity along the basal layer of epithelium. There are numerous invaginations of epithelium into the fibrous wall of this fragmented cystic tumour, but there are no unequivocal separate nests or groups of epithelium within this fibrous stroma (see comment). Centrally within the invaginations and superfically in the epithelial lining there is stellate reticulum which shows multiple areas of squamous metaplasia. There is no invasion of bone by tumour. Comment: Due to the fragmented nature of the specimen, assessment of the invaginations of the epithlium into the fibrous wall of the tumour is difficult, however the separate nests are favoured to be cross cut sections of invaginations of the epithelium into the fibrous. The appearances are consistent with the unilocular luminal type of ameloblastoma.

DIAGNOSIS: Left marsupialization plus tooth: Ameloblastoma; favoured to be unicystic luminal type.

Case Discussion

Ameloblastomas are benign, locally aggressive tumours that arise from the mandible, or less commonly from the maxilla. Usually they present as a hard painless lesion near the angle of the mandible in the 3rd to 5th decades of life.

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Case Information

rID: 33677
Case created: 20th Jan 2015
Last edited: 5th Mar 2016
System: Head & Neck
Inclusion in quiz mode: Included

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