Capillary Venous Malformation With Secondary Aneurysmal Bone Cyst of Temporal Bone.

Aneurysmal bone cysts (ABCs) arising from vascular malformation are extremely rare, and none have been reported in the literature in English till now. We report a very rare case of secondary ABC of left temporal bone in a 5-year-old Caucasian boy who presented with a left sudden facial palsy associated with a painless non-tender mass of the left temporo-parietal region. The computed tomography (CT) and magnetic resonance imaging (MRI) features were suggestive of ABC secondary to a capillary venous malformation, with concurrent involvement of the squamous, mastoid, and petrous portions of the temporal bone. Surgical resection was performed. On follow-up, the patient was found to be doing well.