A 12-year-old female visited a dentist for a routine checkup. Radiographic examination revealed a large lesion in the left mandible.
Joen Iannucci Haring, DDS, MS
The patient did not have an erupted 12-year molar present in the mandibular left quadrant. The patient denied any history of signs or symptoms associated with this region. The patient appeared to be in a general good state of health, with no significant medical history. The patient`s dental history included regular dental examinations and routine dental treatment. At the time of the dental appointment, the patient was not taking medications of any kind.
The patient`s vital signs were all found to be within normal limits. Examination of the head and neck region revealed no enlarged or palpable lymph nodes. Examination of the oral soft tissues revealed no unusual findings. No bony abnormalities were noted.
The patient`s most recent bite-wing radiographs were dated June 1996, and no panoramic radiograph had been exposed to date. After a thorough clinical examination and a review of the patient`s medical and dental histories, a panoramic radiograph and four bite-wings were ordered.
Examination of the panoramic radiograph revealed a large, well-defined radiolucency in the left mandible. The lesion was seen surrounding impacted tooth #18 (see radiograph).
Based on the clinical and radiographic information available, which one of the following is the most likely diagnosis?
* adenomatoid odontogenic tumor
* ameloblastic fibro-odontoma
* ameloblastic fibroma
* cementifying fibroma
The ameloblastic fibroma is a benign odontogenic tumor of epithelial and mesenchymal origin. This neoplasm evolves from elements that are normally involved in the formation of teeth. The actual histogenesis of this lesion is uncertain. The ameloblastic fibroma is an uncommon tumor.
The ameloblastic fibroma is most often seen in young patients in the first two decades of life; males are affected more frequently than females. The ameloblastic fibroma is seen in association with the crown of an impacted tooth in 50 percent of cases. This lesion is most often found in the posterior regions of the jaws; the mandible is affected far more frequently than the maxilla. Seventy percent of all cases are identified in the posterior mandible.
The ameloblastic fibroma is a slow-growing, solitary lesion. Pain is usually not a feature. Bony expansion may or may not be present, depending on the size of the lesion. Only large lesions are associated with swelling of the jaws.
The ameloblastic fibroma may appear as a unilocular or multilocular radiolucent lesion with well-defined and sclerotic borders. The ameloblastic fibroma does not have a radiopaque component. The size of the ameloblastic fibroma is variable. When viewed on a dental radiograph, this lesion is typically seen in association with an impacted or unerupted tooth.
The ameloblastic fibroma cannot be diagnosed from its radiographic appearance alone. All lesions identified on a dental radiograph must be documented in the patient record and described in terms of appearance, location and size. Biopsy and surgical removal must be recommended to the patient.
Biopsy and histologic examination of the lesion is necessary to make a definitive diagnosis. Histologically, the ameloblastic fibroma exhibits cords of odontogenic epithelium, often in an anastomosing arrangement. Other lesions that may be considered in the differential diagnosis for the ameloblastic fibroma include the dentigerous cyst, adenomatoid odontogenic tumor, odontogenic keratocyst and the ameloblastic fibro-odontoma.
The ameloblastic fibroma is a tumor and must be treated. Surgical removal of the lesion is the treatment of choice. There appears to be a substantial risk for recurrence following surgical removal; approximately 20 percent recur after removal. In addition, approximately 50 percent of the cases of the rare ameloblastic fibrosarcoma develop as a recurrence of the ameloblastic fibroma.
Joen Iannucci Haring, DDS, MS, is an associate professor of clinical dentistry, Section of Primary Care, The Ohio State University College of Dentistry.