Adenoid Cystic Carcinoma of Maxillary Sinus Misdiagnosed as Chronic Apical Periodontitis.

Sometimes pain originating from a non-odontogenic pathologic condition is mistaken as endodontic illness, leading to misdiagnosis. The patient can misinterpret the pain as originating from a site different from the actual site, which is known as referred pain. However, the clinician managing pain in the orofacial region needs to be well-informed about the typical signs and symptoms of non-odontogenic diseases and to be able to make the correct referral when necessary for proper diagnosis and treatment. A 43-year-old man presented to the department of conservative dentistry complaining of dental pain. Despite nonsurgical root canal treatment and curettage, he complained that the pain had spread to an area inclusive of the right side of the head and face and the right eye. The patient's pain differed from the typical endodontic pain. Therefore, the patient received a diagnosis of non-odontogenic pain and was referred to the pain clinic. Brain magnetic resonance imaging and parotid contrast images showed a mass in the right maxillary sinus. In addition, destruction in the hard palate and alveolar recess adjacent to the sinus floor was found. Infiltration into the cavernous sinus through the pterygopalatine fossa was seen. A neurosurgeon partially removed the mass by performing an osteoplastic craniotomy on the right occipital bone with the patient under general anesthesia. On the basis of the biopsy results, an adenoid cystic carcinoma was diagnosed.