Aneurysmal bone cyst.pptx

Aneurysmal Bone Cyst

1. Aneurysmal bone cyst

2. Defenition They are cysts which is locally destructive, blood-filled reactive lesions of bone and are not considered to be true neoplasms . The term aneurysmal derived from its macroscopic appearance- sponge like tumour with numerous giant cells.

3. Etiology It was first recognized by Jaffe and Lichtenstein(1942) True etiology of ABC is not known. It is not a cyst and is called an aneurysm (quite wrongly) only due to characteristic of expanding the bone into “aneurysm” shape and that it is filled with blood

4. Incidence and Demographics ABC is found at any age Around 75% before 20 years and rare after 30 years. Female : Male :: 2:1 Any bone may be involved, but the most common locations include the proximal humerus , distal femur , proximal tibia, and spine Around 12-30% of ABCs involve spine that represents only 1.4% of Primary vertebral column tumours

5. Primary ABCs They are driven by upregulation of the  ubiquitin-specific protease   USP6  (Tre2) gene on 17p13 when combined by a translocation with a promoter gene. Most commonly described translocation t(16;17)(q22;p13) leading to juxtaposition of promoter region CDH11 on 16q22

6. Secondary ABCs N ot considered a neoplasm because no known translocation has been identified It can be associated with other tumours .

7. Associated with other tumours (30% of times ) Giant cell tumor (GCT) of bone Fibrous dysplasia Chondroblastoma Osteoblastoma Nonossifying fibroma ( NOF) Fibrous histiocytoma Chondromyxoid fibroma Simple bone cyst Giant cell reparative granuloma Telangiectatic osteosarcoma

8. Epidemiology 75% of patients are < 20 yrs . Anatomical location ~15 % seen in spine   >60% in long bones (Femur and tibia being most common) 51% occurrs in the lower extremities, 22.5% in upper extremities Usually in Metaphysis Metatarsal and Calcaneus are the most common locations in the foot  

9. Epidemiology Spine : Most commonly in thoracolumbar region Cervical spine involved in 30-40% 60 % of anuerysmal bone cyst occur in posterior elements Half of the cases involve more than 1 vertebra

10. Presentation Patients usually presents with pain ,mass, a pathological fracture or a combination of all in the affected area. Neurological symptoms may develop involving nerve typically in spine. Other findings include: Deformity Decreased movement ,weakness or stiffness Warmth over affected area

11. Clinical Features Patients commonly have pain and swelling at the site Neurological symptoms may be seen as primary complaint in ABCs affecting the vertebrae Unusually patients may present with a pathological fracture at the site of ABC

12. Gross Pathology Specimens reveal a thin osseous shell surrounding a honeycombed sponge-like mass filled with blood

13. Histology ABCs consists of blood-filled spaces variable size that are separated by connective tissue containing trabeculae of bone oseoid tissue and osteoclast giant cells. They are not lined by endothelium . Cavity lining by numerous   benign giant cells  / spindle cells  / thin strands of woven (new) bone present

14. Development of ABC It follows 3 stages Initial phase : Osteolysis without peculiar findings . Growth phase: Rapid increase in size of osseous erosion . Enlargement of involved bone. Formation of shell around central part of lesion. Stabilization phase Fully developed radiological pattern.

15. Imaging Modalities X-Ray CT scan MRI Nuclear Imaging Angiography

16. X-Ray Appearance ABC is normally placed in the metaphysis and appears as a osteolytic lesion. The periosteum is elevated and the eroded to a thin margin. The expansile nature of the lesion is often refleced by a "blown-out " or "soap bubble” appearance . The lesion rarely penetrates the articular surface or growth plate .

17. Evolution of ABCs ( Radiologically ) Incipient phase (incidentally found): There is a small nonexpansile intramedullary lytic lesion with distinctive elevation of periosteum Growth phase: Rapid growth and lysis of bone that present as cortical blowout in “accelerated” phenomenon of ABC The Codman’s triangles may be prominent at the ends Stable phase: Expanded bone with a “ shell” around the lesion along with trabeculations coursing within it (coarse soap-bubble appearance)

18. Evolution of ABCs Stable phase: Expanded bone with a “ shell” around the lesion along with trabeculations coursing within it (coarse soap-bubble appearance) The Healing Cyst: ( self-resolution or following treatment)shows progressive ossification , resulting in a coarsely trabeculated bony mass often with mineralized matrix The cyst may invaginate into normal bone and to epiphysis through growth plate or extend into soft tissue

19. Capanna et al. described five “morphologic types” based on the radiographic findings: Type I : Central metaphyseal lesion well-contained within bone with intact bone cortices . Type II: Lesion gives an inflated appearance to bone with cortical thinning. Type III: Eccentric metaphyseal location with unaffected cortex . Type IV: Subperiosteal extension but cortex intact rarely seen in the diaphysis. Type V: Metadiaphyseal location blowout appearance, cortical breach present and cyst may invaginate into nearby bone

20. Capanna et al. Classification based on Morphology

21. Computed Tomography (CT) Cross-sectional CT is the most useful imaging examination , It can demonstrate the intraosseous and extraosseous lesion. CT can be used to determine the nature of the matrix of especially when tumors are in complex locations, such as facial skeleton , spine, thoracic cage, and pelvis . Spinal CT can demonstrate stenosis of the spinal canal due to involvement of the posterior elements.

22. MRI MRI can demonstrate the characteristic fluid-fluid levels exquisitely, as well as identify the presence of a solid component and concerning features suggesting an aneurysmal bone cyst-like appearance of another tumor entity.

23. MRI Demonstrates the typical blood fluid levels seen on an MRI scan of ABC

24. Treatment T he treatment options are multiple and best one for a patient needs to be individualized The inactive cysts have complete periosteal shell and sclerotic bone margins The active cysts have incomplete shell and aggressive lesions have indefinite margins Inactive lesions : spontaneous regression seen Active and aggressive ABCs- NEED TREATMENT

25. Percutaneous methods For Inducing sclerosis in the cyst and secondary mineralization (healing ) They have advantage particularly in the juxtaphyseal location and difficult surgical sites Alcoholic solution of zein has shown good result Side effects :percutaneous fistulation , local abscess formation, and sometimes embolization is seen. Healing takes 6–18 months depending on the size of initial lesion Percutaneous methods not to be used in patients with rapid expansion impending fractures patients allergic to drug.

26. Percutaneous sclerotherapy with P olidocanol is a safe alternative to conventional surgery for the treatment of an aneurysmal bone cyst. It can be used at surgically-inaccessible sites and treatment can be performed on an out-patient basis.

27. Demineralized bone particle It is instilled into the lesion as a paste of allogenic bone powder and autogenous bone marrow to induce healing. No curettage or extensive surgery is done It is expected that the bone grafting material promotes ossification at a pace faster that the native rate of ABC expansion

28. Curettage and Bone Grafting It had been the gold standard of treatment that is still used to compare efficacy of other methods It is supplemented with the use of high-speed burr, or extended curettage with adjuvants [peroxide, phenol, cryotherapy , zinc chloride,hypochlorite , PMMA to reduce recurrence rate Selective arterial embolization has been used for reducing the blood loss in large cysts but should not be used to rely upon for inducing healing Growth plate can get damaged while treating the juxtaphyseal lesions

29. Curettage and Bone Grafting

30. Curettage and Bone Grafting Complication of curettage and bone grafting for ABC : The growth plate got damaged during the index lesion leading to premature fusion and growth abnormalities of the bone

31. Marginal en bloc resection It can be done in expendable bones ( fibula , clavicle, rib, pubic ramus) It has got the lowest recurrence rates. Sub periosteal resection is possible in children which can be simultaneously reconstructed with fibula

32. Radiation therapy It has been found effective in inducing healing and ossification It should be abandoned for high likelihood of inducing radiation sarcoma

33. Solid ABCs A third variant called “solid” ABC have been described(coined by Sanerkin et al.) in 1983 Containing , lacy, chondroid like material seen in conventional ABC, but without the typical vascular and cyst like cavities . Represent 5–10% of the ABCs Nevertheless a fourth variant called the “ soft tissue ABCs ” has also been reported

34. REFERENCE Campbell’s Operative Orthopaedics Apley & Solomon’s System of Orthopaedics and Trauma Essential Orthopaedics by Manish Kumar Varshney Orthobullets.com

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