Science and Education Publishing American Journal of Medical Case Reports 2374-216X 4 6 2016 6 25 Chondroblastoma of Diaphysis of Tibia; Case Report 215 217 EN Heidarali Esmaeili Haniyeh Amidfar Assissstant of Pathology, Iran Mehrdad Yavarikia Atiyeh Amidfar AJMCR2016468 10.12691/ajmcr-4-6-8 2016 2 28 2016 4 19 2016 6 23 Background: Chondroblastoma is a rare benign cartilaginous neoplasm that considered for approximately 1% of all bone tumors and characteristically emerges in the epiphysis of a long bone, especially the hummeros, femurand tibia.Only rare cases have been reported in the diaphyseal region. Case Report: We report a case of diaphyseal one in a 13 years old girl that admitted ith brief pain and deformities in left leg. Radiographic examinations disclosed a multiloculated osteolytic lesion in left tibia. Conclusion: Histologicak findings revealed proliferation of polygonal cells in the cartigenous background with few Giant cells.