An osteosarcoma (OS) or osteogenic sarcoma (OGS) (or simply bone cancer) is a cancerous tumor in a bone. Specifically, it is an aggressive malignant neoplasm that arises from primitive transformed cells of mesenchymal origin (and thus a sarcoma) and that exhibits osteoblastic differentiation and produces malignant osteoid.Osteosarcoma is the most common histological form of primary bone sarcoma. It is most prevalent in teenagers and young adults. Signs and symptoms
Many patients first complain of pain that may be worse at night, may be intermittent and of varying intensity and may have been occurring for a long time. Teenagers who are active in sports often complain of pain in the lower femur, or immediately below the knee. If the tumor is large, it can present as overt localised swelling. Sometimes a sudden fracture is the first symptom because the affected bone is not as strong as normal bone and may fracture abnormally with minor trauma. In cases of more deep-seated tumors that are not as close to the skin, such as those originating in the pelvis, localised swelling may not be apparent. Causes
Several research groups are investigating cancer stem cells and their potential to cause tumors along with genes and proteins causative in different phenotypes. Radiotherapy for unrelated conditions may be a rare cause.
Brazilian hemorrhagic fever (BzHF) is an infectious disease caused by Brazilian mammarenavirus, an arenavirus. Brazilian mammarenavirus is one of the arenaviruses from South America to cause hemorrhagic fever. It shares a common progenitor with Argentinian mammarenavirus, Machupo mammarenavirus, Tacaribe mammarenavirus, and Guanarito mammarenavirus. It is an enveloped RNA virus and is highly infectious and lethal. Very little is known about this disease, but it is thought to be transmitted by the excreta of rodents. This virus has also been implicated as a means for bioterrorism, as it can be spread through aerosols.As of 2019, there had only been four documented infections of Brazilian mammarenavirus: two occurred naturally, and the other two cases occurred in the clinical setting. The first naturally occurring case was in 1990, when a female agricultural engineer who was staying in the neighborhood of Jardim Sabiá in the municipality of Cotia, a suburb of São Paulo, Brazil contracted the disease (The virus is also known as "Sabiá Virus"). She presented with hemorrhagic fever and died. Her autopsy showed liver necrosis. A virologist who was studying the womans disease contracted the virus but survived. Ribavirin was not given in these first two cases. Four years later, in 1994, a researcher was exposed to the virus in a level 3 biohazard facility at Yale University when a centrifuge bottle cracked, leaked, and released aerosolized virus particles. He was successfully treated with ribavirin.A fifth case, also naturally acquired in upstate São Paulo, was reported in January 2020.