Oral Pathology Laboratories

This 15 year old girl noticed a progressive swelling developing in the mucobuccal fold over the last year and one-half. It was firm and non tender. The radiograph revealed a well-defined cystic radiolucent lesion between the cuspid and bicuspid teeth causing displacement of both roots. There was no history of any previous extraction in this area.

Differential Diagnosis:

Adenomatoid Odontogenic Tumor
Calcifying Odontogenic Cyst
Cementifying or Ossifying Fibroma
Odontogenic Keratocyst
Ameloblastic Fibroma

The presence of a cystic, well-delineated lesion warrants the above differential diagnosis. Those lesions which are often multilocular can probably be excluded. The age, sex, and location should also be taken into account in this case.

Histology:

Slide 1 (low power, H&E). There are a variety of patterns present. The most obvious are ductal structures lined by cuboidal epithelium. There are also nodules of epithelial cells interspersed by slender shaped cells.

Slide 2 (medium power, H&E). A ductal structure is present on the right. Several nodules are seen in the center of the field with streaming slender cells separating them. At the left, there is a structure with tall cuboidal cells at the periphery which resemble ameloblasts. Above these cells are found an amorphous "oid" material.

Slide 3 (high power, H&E). High power view of one of the ductal structures which is lined by cuboidal to columnar odontogenic epithelium. Note: Many of these tumors contain calcifications which may appear on x-ray examination as radiopaque foci.

Diagnosis: Adenomatoid Odontogenic Tumor