Osteosarcoma may show tumorous bone formation, among other features; and Mixed tumors with overlapping morphologies and similar phenotypes, mainly including Mesenchymal chondrosarcoma, teratomas, malignant triton tumors, and neuromuscular vagal hamartoma: Mesenchymal chondrosarcoma demonstrates negative expression of myogenic markers and molecular detection shows HYE1-NCOA2 fusion gene. This evidence concerns the gene NCOA2 and hamartoma.