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A Non-expansile Radiolucency of the Posterior Mandible

Case Challenge Number: 44

Diagnostic Information

History of Present Illness The patient is asymptomatic and in good general health, has no known drug allergies, and does not take any medications daily. The lesion was an incidental finding on the radiographic survey at the initial orthodontic consultation. Clinical and Radiographic Findings The patient was evaluated for a radiolucent lesion at the right mandibular second molar area associated with impacted tooth #31. No bony expansion was noted clinically. The rest of her intraoral and head and neck examination was unremarkable. A panoramic radiograph revealed a unilocular radiolucency adjacent to but not associated with the impacted #31 (Figure 1).

Case Challenge 44 - Content - Diagnostic Information - Figure 1

Figure 1. Note the radiolucency distal to roots of tooth #30 (arrow).

A cone-beam CT examination revealed a 1.5-cm well-defined radiolucent area located lingual and distal to the roots of tooth #30 and mesial to the crown of the impacted tooth #31 (Figure 2). There was some expansion and thinning of the lingual cortical plate but no root resorption.

Case Challenge 44 - Content - Diagnostic Information - Figure 2

Figure 2. Cone beam CT showing expansion adjacent to impacted tooth #31.

Histopathological Findings An incisional biopsy was performed revealing an odontogenic neoplasm composed of a myxomatous connective tissue stroma containing nests and cords of cuboidal to columnar epithelium arranged in a pattern suggestive of early enamel organ development (Figures 3 and 4).

Case Challenge 44 - Content - Diagnostic Information - Figure 3

Figure 3. Numerous nests of odontogenic epithelium in a myxomatous stroma.

 Case Challenge 44 - Content - Diagnostic Information - Figure 4

Figure 4. The appearance of the epithelium is reminiscent of the developing enamel organ.