An injection-site sarcoma is a commonly occurring tumor that typically arises secondary to vaccine administration or other injections. These tumors were once known as vaccine-site sarcomas, vaccine-associated fibrosarcoma or vaccine-associated sarcomas, however these terms are now considered to be outdated due to the incidence of tumors arising from injections that are not vaccinations.

The incidence of the development of these tumors is 1 in 10,000 patients however some resources indicate the incidence being as low as 1 in 1000 patients. There is some evidence to show that there may be a genetic predisposition for the development of these tumors.

Diagnosis is made with histopathologic evaluation of the tissue. This along with location of the tumor and vaccine history are used to make the diagnosis. Aggressive surgical excision is recommended (rather than incisional biopsies). In some cases, advanced imaging such as CT scans may be required to fully identify the extent of the tumor and aid in complete excision

Treatment for Injection-site sarcomas include surgical excision, sometimes preceded by radiation therapy. In some cases radiation is recommend post-excision as well to control incompletely excised tumor.

Some complications associated with injection-site sarcomas include dehiscence (opening up) of the surgical sites, infection at the surgical site and secondary radiation effects.

The prognosis of injection-site sarcomas depends upon the stage and location of the tumor.