en Orthopedic Surgery Orthopedic Surgery Original Research Original Research <p> <strong> Abstract </strong><strong></strong></p><p> <strong> Background: </strong>Parosteal osteosarcoma is rare low-grade malignancy which arises </p><p>  on the surface of the metaphysis of long bones it has a low propensity to metastasize. </p><p>  Different surgical treatment options including marginal resection, wide resection </p><p>  and amputation were recommended for the tumor. The purpose of the study was to </p><p>  assess the results of different surgical treatment of the lesion. </p><p> <strong> Methods: </strong>Thirty five consecutive patients with parosteal osteosarcoma were </p><p>  managed with four surgical techniques (Marginal resection, wide resection and prosthesis, wide resection and allograft application, and amputation) between 1378 - </p><p>  1387, and the results were retrospectively reviewed. The mean age of the patients </p><p>  when the surgery was performed was 30.37 (range, eleven to seventy one years), and </p><p>  the mean duration of postoperative follow - up was 51 months (range, eight months to </p><p>  ten years). </p><p> <strong> Results: </strong>The mean time between the onset of symptoms and initial physician encounter </p><p>  was 15.98 months (range, 1.5 months to 60 months). None of the patients had </p><p>  metastasis preoperatively while three pulmonary metastases were detected postoperatively. Six patients had regional tumor recurrence postoperatively. The mean time of the recurrence postoperatively was 18.8 months (range, nine months to forty eight months). Three of thirty five patients assessed in the study died of pulmonary metastasis. All had dedifferentiated grading with different staging (Two patients had a </p><p>  stage of IIB and one with IIA). Medullary invasion was seen in one of them. One of </p><p>  the three patients was treated with Indomethacin for two years due to the misdiagnosis </p><p>  of myositis ossificans. </p><p> <strong> Conclusion: </strong>Wide resection of parosteal osteosarcoma produces a satisfactory </p><p>  long - term out come. However, individually - based treatment should be selected for </p><p>  each patient with parosteal osteosarcoma. </p><p>  </p> parosteal osteosarcoma, treatment,outcome 11 16 http://mjiri.iums.ac.ir/browse.php?a_code=A-10-1-93&slc_lang=en&sid=1 Sam Haji aliloo Sami 20031947532846001912 20031947532846001912 No Iran University of Medical Sciences, Tehran, Iran. Mikail Alt Jafarbay 20031947532846001913 20031947532846001913 No Mehdi Ramezan Shirazi Mehdi.shirazi@yahoo.co.uk 20031947532846001914 20031947532846001914 Yes Shafa Yahyaian Hospital, Baharestan Sq., Tehran, Iran Hajir Gharati 20031947532846001915 20031947532846001915 No