M85: Other disorders of bone density and structure

M85.5: Aneurysmal bone cyst

Aneurysmal bone cyst is a unique and rare non-cancerous condition affecting the bones. Often seen in children and young adults, the disease presents itself as a blood-filled, balloon-like growth within the bone, hence the term 'aneurysmal'. It can occur in any bone in the body but it is most commonly seen in the long bones of the arms and legs, the spine, and the pelvis. Patients may experience pain, swelling, and a decreased range of motion in the affected area. In severe cases where the spine is affected, it may lead to neurological complications due to the pressure on the spinal cord. This cystic lesion within the bone grows progressively and can cause significant bone weakening if left untreated, potentially leading to fractures. The exact cause of an aneurysmal bone cyst is still not fully understood by medical professionals.