Primordial Odontogenic Tumor of Mandible; A Case with Proposed Diagnostic Criteria

Dear Editor Primordial odontogenic tumor (POT) has been included as a new entity in a recent WHO (2017) classification of odontogenic tumors under benign mixed mesenchymal and epithelial tumors.1 Although there is controversy regarding the true nature of POT as a newly-recognized embryonal neoplasm of immature dental tissue exhibiting progressive growth potential or just a histopathological variant of ameloblastic fibroma, or odontogenic myxoma/fibroma.2 Only 8 cases of POT have been reported in the literature so far. A 17-year-old boy referred to our institution with a painless swelling of the left lower back region of his jaw that he had been suffering from for 6 months. Family history and medical history of the patient was not contributory to his present symptom. Intra–oral examination revealed a soft tissue gingival growth extending from tooth #34 to #36 measured about 3×2 cm. The swelling was firm and too hard with no signs of discharge and ulceration. A panoramic radiograph revealed that a large multilocular well defined radiolucent lesion of right posterior mandible extending from the mesial root of #34 to the angle of the mandible surrounding unerupted #38. Resorption of the roots of #35, #36, and #37 was noted. The periphery of the lesion was well defined and not surrounded by any sclerotic border. The internal aspect of the lesion was multilocular with large size locules (Figure 1A). Based on the radiographic examination, a provisional diagnosis of unicystic ameloblastoma was made.3 Incisional biopsy was done but the resected tissue was found to be insufficient to make a histopathological diagnosis. Based on the suggestion of the surgeon, the incisional biopsy was not repeated. Enucleation of the lesion was done along with the extraction of #46 under general anesthesia; the ID canal was not preserved. The defect was restored by reconstruction plates. The follow-up period of 6 months was uneventful. The resected specimen was sent for histopathological evaluation. Histopathological examination of hematoxylin staining soft tissue sections revealed a loose and myxoid connective tissue stroma covered by columnar epithelium of a single layer, the epithelium resembled inner enamel epithelium (Figure 1B and Figure 2). Letter to the Editor