12/22/2010 Delayed tooth eruption associated with an ameloblastic fibro-odontoma (AF-O)

Resident: J. Hencler
Date: 12/22/2010

Article title: Delayed tooth eruption associated with an ameloblastic fibro-odontoma (AF-O)
Author: Flaitz DDS, MS; Hicks MD, DDS, MS, PhD

Journal: Pediatric Dentistry-23:3, 2001
Major topic: Oral Pathology
Type of Article: Case Report

Main Purpose:
Describe the clinical and radiographic features of an AF-O in a young child and discuss an age appropriate differential diagnosis.

Case History:
A healthy, 31 month-old Hispanic boy was referred for evaluation of an unerupted left mandibular primary canine (#M). EOE revealed mild facial asymmetry of the lower1/3. IOE revealed both buccal and lingual cortical expansion of the left mandible with lingual displacement of the lateral incisor and distal displacement of the molars. Palpation revealed an asymptomatic, hard enlargement covered by normal mucosa. A periapical radiograph demonstrated a localized radioluceny with dilacerations of the mesial root of the primary first molar and posterior displacement of the developing premolar. An occlusal radiograph reveals an expansile, mixed radiolucent/radiopaque lesion surrounding the crown of an inferiorly displaced, unerupted canine. Based on these findings, the child was referred for surgical excision under GA. Histopathological finding included a tumor with cords/islands of odontogenic epithelium, conglomerate foci of enamel and dentin, and tiny tooth-like structures. Loose and cellular connective tissue stroma resembled a dental papilla and a well formed primary canine was associated with the tumor. A diagnosis of AF-O was made on these microscopic findings.

Key points in the article discussion:
The AF-O is an uncommon odontogenic tumor that resembles an ameloblastic fibroma and a complex odontoma. Most cases occur in children with a mean age between 8-11 years-old but cases as young as 9 months have been reported. AF-O occurs equally in both jaws but favors the anterior region in the maxilla and the posterior region in the mandible. Typically, a slow growing tumor, common clinical findings include painless swelling and failure of one or more teeth to erupt. Radiographic presentation varies from unilocular to multilocular radiolucency with well-defined margins and variable amounts of radiopaque material. The irregular or globular calcifications are usually located in the center of the lesion. Treatment of AF-O usually involves conservative curettage. Large lesions may require a surgical splint to prevent jaw fracture. Recurrences following conservative surgery are uncommon and the prognosis is excellent for this tumor.

Differential Diagnosis:
Other odontogenis lesions in children that present as radiolucent lesions with irregularto globular radiopacities include the adenomatoid odontogenic tumor (AOT), the calcifying odontogenic cyst (COC), and the complex odontoma.
(1) The complex odontoma is the most common and usually occurs in the first 2 decades of life. Considered to be a developmental anomaly or hamartoma the complex odontoma has a predilection for the pericoronal molar region. Most odontomas are asymptomatic and are diagnosed because of delayed eruption of a tooth. A developing odontoma may be difficult to distinguish from an AF-O, both radiographically and microscopically. An important difference between an odontoma and AF-O is that odontoma is smaller and minimally expansile. Local curettage is recommended treatment and recurrence is rare.
(2) AOT occurs predominantly in children during the 2nd decade with delayed tooth eruption as a symptom. This benign tumor has a distinct preference for the anterior jaws, in particular, the maxillary canine region. Many AOTs are small and don’t produce clinically significant distortion of the surrounding bone. AOTs typically present as a well-delineated, unilocular radiolucency around the crown of a developing tooth with fine flecks of calcification referred to as a “snowflake appearance”. EXT of involved tooth and enucleation of the tumor are the recommended treatment. Recurrences are rare.
(3) COC is an uncommon lesion that exhibits variable clinical presentation. Although cystic, benign and malignant neoplastic subtypes are defines. When COC occurs in young children, the cystic type is most common and usually associated with an odontoma. This cystic lesion usually occurs in the anterior region of the jaws with a peak incidence in the second and third decades. Radiographic features of COC include a unilocular or multilocular radiolucency that is associated with an unerupted tooth in 1/3 of cases. Approximately half of all COCs are associated with irregular or tooth-like opacities; however, if associated with an odontoma, calcifications are a constant feature. Asymptomatic expansion of the cortical bone, along with root resorption or divergence may be seen. In general, COC occurring in young children are treated by simple enucleation with uncommon recurrence.

Assessment of article: Very interesting case report including a detailed differential diagnosis. This was a good review of oral lesions that we should consider when a patient presents with an unerupted primary tooth.