Thesis (M.Sc.) - Cairo University - Faculty of Oral and Dental Medicine - Department of Oral and Maxillofacial Surgery

Osteosarcomas and chondrosarcomas are two of the most common types of primary bone malignancies. Osteosarcoma is the most common oral malignancy encountered by oral and maxillofacial pathologists after squamous cell carcinoma. Chondrosarcoma incidence as a primary bone malignancy usually comes following osteosarcoma. Osteosarcoma is a primary bone malignancy of mesenchymal stem cells that produces bone. Its diagnosis is based on the production of osteoid from the malignant cellular stroma. Chondrosarcoma on the other hand, is a malignant neoplasm that arises from mesenchymal cells that undergo partial differentiation to form chondroblastic tissue without osteoid production. Chondroblastic osteosarcoma is a type of osteosarcoma that forms pockets of osteoid in addition to chondroblastic differentiation. Chondroblastic osteosarcoma and chondrosarcoma are two overlapping tumors that are usually misdiagnosed due to the presence of chondroblastic tissue in both of them in addition to the presence of osteoid arising from the malignant stroma in the chondroblastic osteosarcoma. In the absence of a specific diagnostic marker that discriminates accurately between chondoblastic osteosarcoma and chondrosarcoma, misdiagnosis of both tumors might occur. Osteosarcoma treatment usually involves neoadjuvant chemotherapy followed by radical surgery, while chondrosarcoma is usually treated, only, by radical surgical resection. In general chondrosarcoma bears a better prognosis than osteosarcoma. Galectins are a large family of proteins. Only galectin-1, -2, -3, -4, -7, -8, -9, -10, -12 and -13 have been identified in humans. They have a long list of functions. In our study, we were concerned with GAL-1. GAL-1 was expressed in human osteoblasts, suggesting that GAL-1 reactivity might identify tumors of osteoblastic origin. Previous demonstrations showed GAL-1 expression in normal and malignant cells, consequently, this work used GAL-1 as a marker of the osteoblastic lineage rather than a marker of malignancy. In this project, we also analyzed the statistical difference in the immunohistochemical expression of GAL-1 in chondroblastic osteosarcoma and chondrosarcoma to serve as a dicriminitive diagnostic test for both tumors

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