FOLH1 and osteosarcoma: Zeng et al., using IHC, analyzed 45 cases of osteosarcoma and 12 of osteofibrous dysplasia (OD), reporting that while no cases of OD were positive for PSMA immune staining, 46% of osteosarcoma cases showed PSMA expression on the endothelial cells associated with the tumor, and this was significantly associated with the tumor size, the risk of developing pulmonary metastases and the worst clinical outcome, suggesting that PSMA expression could be considered a prognostic marker [86].