Expression of tau proteins and tubulin in extraskeletal myxoid chondrosarcoma, chordoma, and other chondroid tumors

Tau proteins are microtubule-associated proteins required for the polymeriz ation of tubulin. The abnormal accumulation of tau proteins in neurofibrill ary tangles is a well-known phenomenon and has been studied extensively. Ho wever the role of tau protein in chondroid tissue and its neoplasia is unkn own. In the present study, 2 extraskeletal myxoid chondrosarcomas (EMCs) 6 chordomas, 6 chondrosarcomas, 3 myxoid chondrosarcomas of bone, 2 osteochon dromas, 6 chondroblastomas, and 2 nonneoplastic adult articular cartilages were immunostained with monoclonal antibodies against tau proteins and tubu lin. The results showed that the coexpression of tau proteins and tubulin w as present only in EMCs (2/2) and chordomas (4/6). Although tubulin was det ected in chondroblastomas (5/6), osteochondromas (2/2), chondrosarcomas (5/ 6), and myxoid chondrosarcomas of bone (3/3), tau expression was absent in these tumors. The perichondrial chondroblasts but not chondrocytes from non neoplastic articular cartilage also localize tau and tubulin with a much we aker staining intensity. The results mainly demonstrate that there is frequ ent expression of tau proteins in some microtubule-rich neoplasms such as E MC and chordoma. The different immunostaining pattern of tau proteins betwe en chordoma and myxoid chondrosarcoma of bone may be useful in the differen tial diagnosis, especially when bath neoplasms occur in the base of skull.