Case report
A 17 year-old female was referred to the Oral and Maxillofacial
Pathology Department, Tehran University of Medical Sciences, Tehran,
Iran, for consultation and diagnosis of a lesion on the right side of
her mandible. The previous histopathologic diagnosis of the lesion was
ameloblastoma. Before the incisional biopsy, the patient’s chief
complaint was a swelling in the right posterior mandible for 2 weeks.
There was no facial asymmetry. In the intraoral examination, a slight
swelling was observed in the right retromolar area. The swelling was
non-tender and was firm in consistency. Panoramic and CBCT radiographs
showed a well-defined radiolucent lesion that contained areas of
radiopacity around the crown of an unerupted third molar. The margins of
the lesion were sclerotic (Figure 1)
In the review of the microscopic slides, a cystic lesion lined by an
odontogenic epithelium which consists of cuboidal to columnar basal
cells with hyperchromatic nuclei demonstrating reverse polarity was
observed. The superficial epithelial cells were loosely arranged and
resembled the stellate reticulum of enamel organ. Aggregations of ghost
cells were notable within the epithelium (figure 2A). Sections of
numerous tooth-germ structures consisting of nests and islands of enamel
organ and dental papilla were also evident in the cyst wall. In some
areas, tooth buds appeared to originate from the cystic epithelium
(figure 2B). There were also sections of developed tooth structures
consists of mature enamel cap and tubular dentine (figure 3). Area of
ectomesenchyme-like cell proliferation similar to dental papilla were
also seen. Based on these histopathologic findings the diagnosis was
developing odontoma arising from a calcifying odontogenic cyst. The
lesion was treated by conservative excision and there was no recurrence
after one-year follow-up (figure 4).