Dentigerous cysts with calcification mimicking odontogenic tumors: differential diagnosis by CT

Objective: This study aimed at clarifying whether we can differentiate dentigerous cysts with calcified substances from other odontogenic tumors that include calcification and the crown of an unerupted tooth by CT findings.

Methods: We retrospectively selected histopathologically confirmed cases that included calcified substances and the crown of an unerupted tooth inside. There were 22 cases with eight pathological categories. Besides seven odontogenic tumors, we included dentigerous cysts, which were usually recognized without calcification within the lesions. We divided the cases into two groups: 14 cases of odontogenic tumors and 8 cases of dentigerous cysts. Cases were analyzed for various CT findings such as continuity with the alveolar crest, bone sclerosis around the lesion, and sizes and shapes of high CT value substances, as well as demographic factors. Comparisons between the groups for each analytical factor were performed.

Results: Dentigerous cysts with dystrophic calcification showed unique CT findings such as bone sclerosis around the lesion, continuity with the alveolar crest, and small scattered calcified substances near the crown of an unerupted tooth, compared with typical dentigerous cysts and other odontogenic tumors. On the other hand, odontogenic tumors showed various patterns in the location and distribution of high CT value substances, and we could only differentiate odontoma using its very high CT values.

Conclusion: Although the patterns of calcification were not the main characteristic findings, it may be possible to differentiate dentigerous cysts with dystrophic calcification from odontogenic tumors by their other characteristic CT findings, and unnecessary extensive surgery can also be avoided.