Introduction: Aneurysmal bone cyst (ABC) is a primary or secondary benign tumor, consisting of an intraosseous cavity, uni or multilocular, with hematic content. It can develop on all bones of the skeleton with, however, a predilection for the long bones and the spine. KOA mainly affects children and young adults, with a slight female predominance. Objective: The aim of this work is to reveal the diagnostic features at the imaging level. Case Report: This is an 11-year-old female patient with no previous pathological history who has presented for 1 year with diffuse maxillofacial pain, with intermittent fluid discharge in the oral cavity. Facial CT scan without and with contrast injection objective a lytic image centered on the lateral wall of the left maxillary sinus bulging into the sinus lumen with a spontaneously hypodense multicompartmental appearance without contrast gain after PDC injection. Conclusion: KAO is a very polymorphic lesion, which presents a diagnostic problem (Aspecific radiological appearance). In spite of the different therapeutic modalities proposed, it is the surgical treatment which exposes less risk of recurrence.