Radiographic opacity in the maxillary sinus is indicative of ailments such as fungal maxillary sinusitis, neoplastic disease, or isolated bone fragments. In this paper, we describe a case of a maxillary sinus polyp with ossification. The diagnosis was based on the histopathological findings and features of an excised specimen with a bone lesion in the maxillary sinus adherent to a dental root on one side. The patient, a 36-year-old woman, was referred to our department for further evaluation of a radiographic opacity in the right maxillary sinus. Our initial examination revealed no subjective symptoms and no organic abnormalities. However, panoramic radiography revealed an opacity in the apex of 6, which computed tomography revealed to be a 20 × 15 mm internally inhomogeneous calcification adhering to a palatal root. Surgical excision of the calcification and apicoectomy of 6 were performed. A lesion adhering between the anterior wall of the maxillary sinus and the palatal root of 6 was found. Histopathological examination of the excised specimen revealed that it was mature bone tissue covered by columnar epithelium. On reviewing these findings, the aforementioned diagnosis was made. Postoperative examinations at 3 years revealed no signs of recurrence.
