Unicystic ameloblastoma: a possible pitfall in periapical diagnosis

Aim To report a clinical case of unicystic ameloblastoma previously misdiagnosed as radicular cyst. Summary A 49-year-old white male was referred to a private practitioner complaining of an asymptomatic bony hard swelling of the left posterior mandible. The patient's dental history indicated that his left mandibular first molar had been extracted approximately 10 years previously. At that time, preoperative radiographic examination demonstrated a radiolucent area of 1.5 cm diameter with well-defined margins involving the distal root of tooth 36. The lesion was diagnosed as cystic and surgery for its removal was advised, but not performed. At presentation, radiography demonstrated a well-defined 3 cm diameter radiolucency extending from the second premolar to the second molar. The lesion was enucleated and histopathological examination confirmed a diagnosis of unicystic ameloblastoma. Key learning points Despite a clinical diagnosis of periapical disease of endodontic origin, a nonendodontic lesion may be present. Unicystic ameloblastoma located on the periapical area of a tooth can lead to a pulpperiapical misdiagnosis, and should be considered in differential diagnosis. All tissue specimens recovered in apical surgery should be submitted to histopathological analysis.