Extraosseous aneurysmal bone cyst of cerebello-pontine angle with USP6 rearrangement

Excerpt

Aneurysmal bone cyst (ABC) is a benign cystic lesion characterized by blood filled cyst-like cavities separated by connective tissue septa containing spindle cells, osteoclast-type multinucleated giant cells and reactive woven bone or osteoid [7]. Most ABCs arise de novo (primary ABC), but others (secondary ABC) are associated with another benign or malignant bone lesion [7]. Most of the lesions are located within the metaphysis of long bones or vertebral bodies of children and young adults [7]. Involvement of cranial bones is not common, but well documented [2]. Giant cell reparative granuloma, which frequently occurs in the jaw bones, has been shown to be a solid variant of ABC [6]. Lesions that are entirely extraosseous or limited to soft tissues are extremely rare and only a few examples are reported in the English language literature [1, 3, 4, 8], none of them intracranial. We present a case of a primary intracranial extraosseous ABC located in the right cerebello-pontine angle (CPA) region of a 25-year-old man. …