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  1. 1. OsteoidOsteoma<br />
  2. 2. Index<br />Introduction<br />Special features<br />Incidence<br />Sites of predilection<br />Symptoms<br />Other Clinical Features<br />
  3. 3. Gross Appearance<br />Microscopy<br />Radiological findings<br />Why relief with aspirin !!!!<br />Differential Diagnosis<br />Treatment<br />Conclusion<br />
  4. 4. Introduction<br />Osteoid osteomas are bone tumors less than 2 cm in greatest dimension and usually occur in patients in their teens and twenties. <br />In fact, 75% of patients are under age 25.<br />Osteoid osteomas can arise in any bone but have a predilection for the appendicular skeleton. <br />
  5. 5. 50% of cases involve the femur or tibia, where they commonly arise in the cortex.<br />
  6. 6. Osteoid osteomas are painful lesions. <br />The pain is caused by excess prostaglandin E2 which is produced by the proliferating osteoblasts. <br />It characteristically occurs at night and is dramatically relieved by aspirin.<br />
  7. 7. Special features<br />Failure to increase in size with time<br />Spontaneous regression<br />Replacement by scar tissue<br />These features are unlike those <br />of other benign tumors <br />suggesting that the etiology <br />still remains an enigma.<br />
  8. 8. Incidence <br />10-11% of all benign bone tumors<br />2.5%-5% of all bone tumors<br />First three decades of life <br />Most common-second decade<br />Most common-in men (2:1)<br />
  9. 9. Sites of predilection<br />Diaphysis of femur and tibia<br />Medial side of neck of femur<br />Posterior elements of spine<br />Humerus<br />Phalanges of hand <br />Fibula <br />Talus<br />Ribs <br />Skull<br />
  10. 10. Symptoms <br />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)<br />Limp <br />Muscular atrophy due to disuse <br />Swelling and warmth if it is superficial<br />
  11. 11. Adjacent joint stiffness<br />Scoliosis<br />In children overgrowth and angular deformities<br />Nerve root compression or cord compression<br />Point tenderness over the lesion<br />
  12. 12. Gross Appearance<br />Cherry red to gray red tissue<br />Overlying cortex distorted <br />Reactive periosteal new bone formation<br />Nidus may vary <br />from few mm to <br />1.5 cm in diameter.<br />Surrounding reactive bone<br /> usually thick hard and <br />extensive..<br />
  13. 13. Microscopy<br />Numerous osteoblasts forming highly irregular trabeculae of osteoid and woven bone<br />Numerous osteoclasts<br />Woven bone trabeculae variably mineralized<br />Calcification more near centre of lesion.<br />
  14. 14. At times no calcification of nidus<br />Surrounding bone shows reactive bone formation which is lamellar bone in contrast to woven bone of nidus<br />Thin zone of fibrovascular tissue between nidus and reactive bone .<br />
  15. 15. Radiological findings<br />Small to round to oval focus of decreased density called nidus .sometimes nidus also sclerotic.<br />Surrounding area of sclerosis which is normal reactive bone .<br />
  16. 16. Lesions usually in diaphysis<br />Mostly cortical sometimes inside medullary canal or subperiosteally<br />Periosteal reaction when occurs is large but smooth in contrast to “codman triangle” of malignant lesions<br />
  17. 17. Bone scan<br />Useful in detecting small lesions<br />“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.<br />
  18. 18. CT scan and MRI<br />Sometimes required to localise the lesion accurately.<br />
  19. 19. Osteoidosteoma. 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 osteoidosteoma in the left lower tibia shows increased activity (arrows) at the site of the lesion. <br />
  20. 20. Osteoidosteomas, 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 <br />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. <br />
  21. 21. Why relief with aspirin !!!!<br />High levels of prostaglandins present in osteoid osteoma which mediate pain receptor pathway<br />Aspirin (salicylates) act as prostaglandin synthetase inhibitors<br />
  22. 22. Differential Diagnosis<br />Osteoblastoma <br />Osteosarcoma<br />EosinophilicGranuloma<br />Ewings Sarcoma<br />Brodie’s Abscess<br />Stress Fractures<br />
  23. 23. Treatment<br />Surgical removal of lesion<br />To relieve pain.secondary manifestations like synovitis ,scoliosis, nerve root compression <br />
  24. 24. Principle of surgery<br />Necessary to remove the “NIDAL” tissue<br />
  25. 25. Surgical options<br />Block resection of the nidus<br />Increases risk of subsequent # if lesion is in cortical bone<br />Alternative method is to shave the reactive bone with sharp osteotome until the nidus is exposed ,then curette the exposed nidus<br />
  26. 26. Intraoperativelocalization of nidus possible with pre operatively injected technetium labelledmethylenediphosphonate and sterile wrapped geigercounter.<br />Intraoperativexrays of excised specimen to document complete removal of nidus<br />
  27. 27. Excision of nidus using CT assisted localization<br />K-wire inserted into the nidus <br />Biopsy punch inserted over k-wire <br />Percutaneous CT guided resection using a trephine 2mm larger then the lesion to ensure complete removal.<br />
  28. 28. Radiofrequency ablation <br />Done percutaneously <br />Initial core needle biopsy after which radiofrequency electrode is inserted through cannula of biopsy needle<br />Temperature at the tip raised to 90 degrees centigrade for 6 minutes<br />Results:claim to be equivalent to surgical excision<br />Used only in extraspinal lesions that are away from neurovascular structures <br />
  29. 29. Conclusion<br />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. <br />