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An aneurysmal bone cyst (ABC) is a benign, expansile, osteolytic lesion characterized by blood-filled cystic spaces separated by connective tissue septa. Though benign, it is locally aggressive and has a risk of recurrence.

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https://youtu.be/RBsEQpXZwjo

Etiopathogenesis

https://doi.org/10.3892/ol.2017.5682

• Primary ABC (70%): Arises de novo; USP6 gene rearrangement (t(16;17)(q22;p13)).
• Secondary ABC (30%): arises from pre-existing lesions like:
  • Giant cell tumor (GCT)
  • Chondroblastoma
  • Fibrous dysplasia
  • Osteoblastoma
  • Non-ossifying fibroma

Epidemiology

Clinical Features

Common locations:

• Metaphysis of long bones (femur, tibia, humerus)
• Spine (posterior elements)
• Pelvis
• Rare: skull, hands, feet
• Pain and swelling
• Palpable mass
• Pathologic fracture