We revealed characteristic CSF1 expression on IHC in only cases of TSGCT and not in GCRTs and GCRT-like lesions such as giant cell tumor of bone, aneurysmal bone cyst, giant cell reparative granuloma, undifferentiated pleomorphic sarcoma, leiomyosarcoma, and myxofibrosarcoma. This evidence concerns the gene CSF1 and myxofibrosarcoma.