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  1. 2. <ul><li>Introduction </li></ul><ul><li>Special features </li></ul><ul><li>Incidence </li></ul><ul><li>Sites of predilection </li></ul><ul><li>Symptoms </li></ul><ul><li>Other Clinical Features </li></ul>
  2. 3. <ul><li>Gross Appearance </li></ul><ul><li>Microscopy </li></ul><ul><li>Radiological findings </li></ul><ul><li>Why relief with aspirin !!!! </li></ul><ul><li>Differential Diagnosis </li></ul><ul><li>Treatment </li></ul><ul><li>Conclusion </li></ul>
  3. 4. <ul><li>Osteoid osteomas are bone tumors less than 2 cm in greatest dimension and usually occur in patients in their teens and twenties. </li></ul><ul><li>In fact, 75% of patients are under age 25. </li></ul><ul><li>Osteoid osteomas can arise in any bone but have a predilection for the appendicular skeleton. </li></ul>
  4. 5. <ul><li>50% of cases involve the femur or tibia, where they commonly arise in the cortex. </li></ul>
  5. 6. <ul><li>Osteoid osteomas are painful lesions. </li></ul><ul><li>The pain is caused by excess prostaglandin E 2 which is produced by the proliferating osteoblasts. </li></ul><ul><li>It characteristically occurs at night and is dramatically relieved by aspirin. </li></ul>
  6. 7. <ul><li>Failure to increase in size with time </li></ul><ul><li>Spontaneous regression </li></ul><ul><li>Replacement by scar tissue </li></ul><ul><li>These features are unlike those </li></ul><ul><li>of other benign tumors </li></ul><ul><li>suggesting that the etiology </li></ul><ul><li>still remains an enigma. </li></ul>
  7. 8. <ul><li>10-11% of all benign bone tumors </li></ul><ul><li>2.5%-5% of all bone tumors </li></ul><ul><li>First three decades of life </li></ul><ul><li>Most common-second decade </li></ul><ul><li>Most common-in men (2:1) </li></ul>
  8. 9. <ul><li>Diaphysis of femur and tibia </li></ul><ul><li>Medial side of neck of femur </li></ul><ul><li>Posterior elements of spine </li></ul><ul><li>Humerus </li></ul><ul><li>Phalanges of hand </li></ul><ul><li>Fibula </li></ul><ul><li>Talus </li></ul><ul><li>Ribs </li></ul><ul><li>Skull </li></ul>
  9. 10. <ul><li>Pain which has characteristic pattern described variously as sharp,dull,boring deep,or intense often worst at night and very frequently relieved by salicylates*(aspirin) </li></ul><ul><li>Limp </li></ul><ul><li>Muscular atrophy due to disuse </li></ul><ul><li>Swelling and warmth if it is superficial </li></ul>
  10. 11. <ul><li>Adjacent joint stiffness </li></ul><ul><li>Scoliosis </li></ul><ul><li>In children overgrowth and angular deformities </li></ul><ul><li>Nerve root compression or cord compression </li></ul><ul><li>Point tenderness over the lesion </li></ul>
  11. 12. <ul><li>Cherry red to gray red tissue </li></ul><ul><li>Overlying cortex distorted </li></ul><ul><li>Reactive periosteal new bone formation </li></ul><ul><li>Nidus may vary </li></ul><ul><li>from few mm to </li></ul><ul><li>1.5 cm in diameter. </li></ul><ul><li>Surrounding reactive bone </li></ul><ul><li>usually thick hard and </li></ul><ul><li>extensive.. </li></ul>
  12. 13. <ul><li>Numerous osteoblasts forming highly irregular trabeculae of osteoid and woven bone </li></ul><ul><li>Numerous osteoclasts </li></ul><ul><li>Woven bone trabeculae variably mineralized </li></ul><ul><li>Calcification more near centre of lesion. </li></ul>
  13. 14. <ul><li>At times no calcification of nidus </li></ul><ul><li>Surrounding bone shows reactive bone formation which is lamellar bone in contrast to woven bone of nidus </li></ul><ul><li>Thin zone of fibrovascular tissue between nidus and reactive bone . </li></ul>
  14. 15. <ul><li>Small to round to oval focus of decreased density called nidus .sometimes nidus also sclerotic. </li></ul><ul><li>Surrounding area of sclerosis which is normal reactive bone . </li></ul>
  15. 16. <ul><li>Lesions usually in diaphysis </li></ul><ul><li>Mostly cortical sometimes inside medullary canal or subperiosteally </li></ul><ul><li>Periosteal reaction when occurs is large but smooth in contrast to “codman triangle ” of malignant lesions </li></ul>
  16. 17. <ul><li>Useful in detecting small lesions </li></ul><ul><li>“ Double density sign” which is a focal area of increased activity with a second smaller area of increased uptake superimposed on it is said to be diagnostic. </li></ul>
  17. 18. <ul><li>Sometimes required to localise the lesion accurately. </li></ul>
  18. 19. <ul><li>Osteoid osteoma. A lateral view (A) of the proximal tibia shows a very dense lesion in the posterior cortex. A darker central area contains a white nidus. This lesion in a 20-year-old man caused pain in this area, relieved by aspirin. B, A nuclear medicine bone scan in a different patient with an osteoid osteoma in the left lower tibia shows increased activity (arrows) at the site of the lesion. </li></ul>
  19. 20. <ul><li>Osteoid osteomas, especially those that arise beneath the periosteum, usually elicit a tremendous amount of reactive bone formation that encircles the lesion. The actual tumor, known as the nidus, manifests radiographically as a small round lucency that is variably mineralized </li></ul>Specimen radiograph of intracortical osteoid osteoma. The round radiolucency with central mineralization represents the lesion and is surrounded by abundant reactive bone that has massively thickened the cortex.
  20. 21. <ul><li>High levels of prostaglandins present in osteoid osteoma which mediate pain receptor pathway </li></ul><ul><li>Aspirin (salicylates) act as prostaglandin synthetase inhibitors </li></ul>
  21. 22. <ul><li>Osteoblastoma </li></ul><ul><li>Osteosarcoma </li></ul><ul><li>Eosinophilic Granuloma </li></ul><ul><li>Ewings Sarcoma </li></ul><ul><li>Brodie’s Abscess </li></ul><ul><li>Stress Fractures </li></ul>
  22. 23. <ul><li>Surgical removal of lesion </li></ul><ul><li>To relieve pain.secondary manifestations like synovitis ,scoliosis, nerve root compression </li></ul>
  23. 24. <ul><li>Necessary to remove the “NIDAL” tissue </li></ul>
  24. 25. <ul><li>Block resection of the nidus </li></ul><ul><li>Increases risk of subsequent # if lesion is in cortical bone </li></ul><ul><li>Alternative method is to shave the reactive bone with sharp osteotome until the nidus is exposed ,then curette the exposed nidus </li></ul>
  25. 26. <ul><li>Intraoperative localization of nidus possible with pre operatively injected technetium labelled methylene diphosphonate and sterile wrapped geigercounter. </li></ul><ul><li>Intraoperative xrays of excised specimen to document complete removal of nidus </li></ul>
  26. 27. <ul><li>K-wire inserted into the nidus </li></ul><ul><li>Biopsy punch inserted over k-wire </li></ul><ul><li>Percutaneous CT guided resection using a trephine 2mm larger then the lesion to ensure complete removal. </li></ul>
  27. 28. <ul><li>Done percutaneously </li></ul><ul><li>Initial core needle biopsy after which radiofrequency electrode is inserted through cannula of biopsy needle </li></ul><ul><li>Temperature at the tip raised to 90 degrees centigrade for 6 minutes </li></ul><ul><li>Results:claim to be equivalent to surgical excision </li></ul><ul><li>Used only in extraspinal lesions that are away from neurovascular structures </li></ul>
  28. 29. <ul><li>Osteoid osteomas’ are considered benign and are normally treated by conservative surgery. However there is a possibility of malignant transformation. This is rare except when treated with radiation, which promotes this complication. </li></ul>