Occipital aneurysmal bone cyst rupture following head trauma: case report.

Aneurysmal bone cysts (ABCs) are benign, expansile, osteolytic lesions that represent 1%-2% of primary bone tumors. Cranial ABCs are even more rare and represent 3%-6% of these unique lesions. The authors describe the case of a 3-year-old girl who presented with an acute posterior fossa epidural hematoma after minor trauma. Imaging workup revealed a previously undiagnosed suboccipital ABC that appeared to have ruptured as a result of her trauma, leading to a life-threatening hemorrhage. To the authors' knowledge, a ruptured ABC has never before been presented in the pediatric literature. In this case report, the authors review the imaging findings, natural history, clinical course, and treatment of these rare lesions.