Discussion
The calcifying epithelial odontogenic tumor (CEOT) or Pindborg tumor has been well documented in the literature since its first description. It is a rare lesion, the reported cases didn’t exceed 4001, and it represents less than 1% of all odontogenic tumors 3. The non-calcifying variant is very rare; it is the least reported one 1. The radiological and histological features of the non-calcifying epithelial odontogenic tumor are distinguished from those of the usual calcified variant. Consequently, there was a diagnostic challenge in the reported case and the diagnosis of a Pindborg tumor was not suspected.
On radiographic examination, Pindborg tumor appears most commonly as a mixed radiopaque/ radiolucent image. Both multilocular and unilocular presentations were described. The association with an impacted tooth was frequently found. The present case was exempt from radiopacities. This radiolucent aspect is insufficient to diagnose a non calcifying variant since it was described in early diagnosed immature lesions, in which calcifications were found on histopathological examination. This radiolucent aspect was also described in some called cystic variant4. This radiolucent aspect may lead to the misdiagnosis of this variant as an odontogenic cyst, like in the reported clinical case.
The most distinctive microscopic feature of classical CEOT is the presence of sheets of polyhedral cells, amyloid globules and Liesegang ring calcifications in the tumor tissue5. According to the literature, non-calcifying cases described are primarily associated with the presence of Clear Cells and Langerhans Cells. This led authors to the definition of variants of this tumor: the Clear Cells variant and Langerhans Cells-rich variant 1.
The absence of calcification does not only pose a diagnostic problem, but also has been suggested to be an indicator of poor differentiation of the tumor. Consequently, the non-calcifying epithelial odontogenic tumor would have more risk of recurrence and requires radical treatment and a long-term follow-up.3
The international literature was reviewed; only 16 cases of non-calcifying epithelial odontogenic tumor were found from 1981 to 2021 and are resumed in table 1. No sex predilection was noted (7 females/ 9 males). Age ranged from 20 to 68 years old. The present reported case adds a female patient aged 40 years old. Ten of the cases were developed in the maxillary bone over seven cases in the mandible, including the present reported case. Histologically, 4 of the reported non calcifying variants contained clear cells, 5 contained Langerhans cells, 2 contained both clear and Langerhans cells, and 5 showed neither clear cells nor Langerhans cells like the reported clinical case. Treatment modalities varied between enucleation and partial resection with 1cm margins to prevent recurrence. Enucleation was preferred as a more conservative approach in the present case since the diagnosis of Pindborg tumor was unlikely suspected before histopathology, especially with the absence of calcification and the sporadic similar reported cases. Also, there were no clinical or radiological signs of aggressivity of the lesion.
Considering the prognostic implications that present the absence of calcifications, close follow-up appointments are mandatory to assess any possible recurrence early. In the literature, no cases of recurrence were reported over follow-up periods ranging from 6 months to 10 years.