bone cysts mcmaster faculty of health 动脉瘤性骨囊肿麦克马斯特大学健康课件

Aneurysmal Bone Cysts (ABCs) Dr. Ted Scriven Sept 8, 2008 ABCs Classified as a benign boney lesion More specifically, “benign-aggressive” Benign-aggressive = marked bone destruction, soft tissue extension or pathologic fractures Etiology Specific translocation 17p13 Can arise de novo, or be associated with another primary: GCT, chondroblastoma, UBC, osteoblastoma, fibrous dysplasia, nonossifying fibroma, chondromyxoid fibroma, osteosarcoma Etiology Result from local circulatory abnormality: Increased venous pressure Local hemorrhage Osteolysis More bleeding Source of bleeding = capilliaries in cyst membrane Hemorrhage progresses to destructive lesion Clinical Picture Age: often M (slight) Location: metaphysis or metadiaphysis of long bones (prox humerus, distal femur, prox tibia) Occasionally iluim or lumbar vertebrae (15 20%) Clinical Picture Mild pain or swelling May have neuro deficits with spinal lesions Duration = weeks years Symptoms may worsen with pregnancy (more blood volume) Investigations Start with thorough Hx & PE Xray: Radiolucent destructive cyst, expands surrounding cortex “Soap-Bubbles” Often eccentric, can be central or subperiosteal Elevated periosteum Thin shell Investigations Bone Scan: Diffuse or peripheral tracer uptake Central area of decreased uptake Angiography: Accumulation of contrast throughout +/- hypervascularity of periphery Absence of viable afferent or efferent vessels Investigations CT Helps deliniate lesion in areas of complex boney anatomy MRI Multiloculated cavities, fluid levels, +/- associated soft tissue mass Helps to differentiate between ABC & UBC DDx UBC Chondromyxoid Fibroma Chondroblastoma GCT Osteoblastoma Talengiectatic Osteosarcoma Pathology Gross: Cavitary w/ blood filled spaces Surrounded by thin layer of bone & raised periosteum Pathology Micro: Hemorrhagic tissue with spaces separated by cellular stroma No endothelial lining or smooth muscle only lining is compressed fibroblasts ALWAYS be sure to examine entire speciman and surrounding area (association with other primaries!) Treatment Curettage & Bone Grafting Caution: lesion prone to heavy bleeding! Tourniquet Pre-op embolization +/- local adjuvent tx for cavity sterilization: Phenol, liquid nitrogen, argon Ressection: If area is expendable (fibula, metatarsal, etc) Radiation: Not routinely used d/t potential for malignant transformation Prognosis If primary: Usually a favourable prognosis Recurrence: Rate after curettage = 14 34% Usually within 6/12, rare after 2 yrs More common in age 15 yo, centrally located lesions, and when c