Huge aneurysmal bone cyst of iliac bone in a mid-aged female.

Aneurysmal bone cyst is a rare nonneoplastic expansile osteolytic bone lesion of unknown etiology. It usually occurs in the first 2 decades of life. The most common sites are the metaphysio-epiphyseal areas of long bones or vertebrae with eccentric expansion. We present a 42-year-old female with a huge aneurysmal bone cyst of the pelvis with dumbbell-shaped expansion on the both side of the iliac bone, which grew rapidly in 6 months. We also review the literature and discuss its prevalence, clinicopathologic characteristics, differential diagnostic problems, optimal treatment, and the potential of recurrence.