Hamadan University of Medical Sciences Avicenna Journal of Dental Research 2423-7582 7 1 2015 06 01 Multiple Calcifying Odontogenic Cysts Involving the Maxillary Sinus 6 6 10.17795/ajdr-25463 EN Masoumeh Zargaran Atefeh Hashemi Mohammad Reza Jamalpour https://orcid.org/0000-0002-0092-0443 Journal Article 10.17795/ajdr-25463 2014 11 19 2014 12 16 Introduction: Calcifying odontogenic cyst (COC) is an uncommon odontogenic lesion, classified in two variants: the cystic variant and neoplastic (solid) variant. Case Presentation: This case report presents multiple COC, which involved the maxillary bone and sinus in a 30-year-old man. Several of these lesions were cystic, while the others were neoplastic in type, and the lesions were removed surgically. Discussion: Based on a literature review available on this topic in English, our case study was found to be the first one with multiple COC, showing both the cystic and neoplastic histopathological variant. Considering the high rate of recurrence of neoplastic COC, the patients should benefit from a long follow-up after treatment.