1、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 associat
2、ed with another primary: GCT, chondroblastoma, UBC, osteoblastoma, fibrous dysplasia, nonossifying fibroma, chondromyxoid fibroma, osteosarcoma,Etiology,Result from local circulatory abnormality:Increased venous pressureLocal hemorrhageOsteolysisMore bleedingSource of bleeding = capilliaries in cyst
3、 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 wit
4、h 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,Investigations,Bone Scan: Diffuse o
5、r 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
6、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: Hemorrha
7、gic tissue with spaces separated by cellular stromaNo 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 bleedi
8、ng! 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 contents not all removed If associated with another primary: Classification, treatment and prognosis based on the other (primary) lesion,
