Cemento-ossifying fibroma with secondary aneurysmal bone cyst of the mandible: A case report of a large intermixed lesion in a 17-year-old female

The intermixed mandibular lesion of cemento-ossifying fibroma (COF) and aneurysmal bone cyst (ABC) is a rare occurrence with dramatic ramifications if left untreated. COF is a benign fibro-osseous neoplasm that predominantly affects the tooth bearing regions of the jaws. It is most commonly observed in women during their third and fourth decades of life. ABC, alternatively, is a vascular lesion characterized by blood-filled spaces within the bone. The coexistence of these two distinct pathologies in the mandible presents diagnostic challenges due to their overlapping radiographic features. Once a diagnosis is obtained, smaller lesions can be enucleated and curettaged, although for larger and mixed lesions, en bloc resection is advised to reduce risk of recurrence. We present a case of a 17-year-old female with an intermixed lesion of the left mandible, undiagnosed for over 1 year, which led to severe facial asymmetry and mass effect on surrounding tissues. Treatment was completed with a left hemimandibulectomy and reconstruction with a custom plate, condylar head and free fibular flap transfer.