Osteosarcoma is the most common malignant primary non hematopeitic tumor of the bone, thereby excluding multiple myeloma as the primary malignant tumor of bone.
It commonly arises from the metaphysics of the long bones and there is a bimodal peak of incidence.
Grossly the appear as bulky grey white tumor with areas of hemorrhage and necrosis. Due to elevation of the periosteum it forms an imaginary triangle called as Codmans triangle . This codman s triangle is a type of periosteal reaction , though commonly seen but not specific for osteosarcomas.
Microscopically you focus on two things. 1) is presence of osteoid and number 2) is the malignant tumor cells having features of anaplasia.
Instagram : https://www.instagram.com/path_logos/