A rare aneurysmal bone cyst of the maxillary sinus: a case report.

Aneurysmal bone cyst (ABC) is a non-neoplastic expansile bone lesion that is common in the long bones; only 2% occurs in the head and neck. We present a case of ABC in a 23-year-old male and describe the clinical and radiological features, histopathology and treatment. Magnetic resonance imaging (MRI) demonstrated multiple internal septations, cysts with fluid-fluid levels of varying intensity, and an intact rim of low-intensity signal completely surrounding the lesion. The tumor was removed by enucleation with resection of the lateral nasal cavity. Histopathologic diagnosis was ABC and fibrous dysplasia. We suggest that MRI is very useful for the diagnosis of ABC. ABC is thought to follow other lesions, and thus when treating ABC, it is important to determine whether any pre-existing lesion has preceded or not; in particular, if the lesion site is in the head and neck region.