Abstract

Immunohistochemical analysis of 24 paraffin-embedded osteosarcomas was studied to evaluate the expression of simple cytokeratin, basal cytokeratin and epithelial membrane antigen(EMA) according to the histologic subtypes and anatomical locations. Mean age of the patients was 18 years. Anatomical locations of the tumors were femur(8), tibia(10), humerus(4), lumbar spine(1), and zygomatic arch(1). Histologic subtypes included osteoblastic(14), fibroblastic(4), chondroblastic(4), epithelioid(1), and mixed osteoblastic and fibroblastic(1). All were positive in the immunohistochemical stain for vimentin. The expression of cytokeratin and/or EMA was found in 10 cases(41.7%) regardless of anatomical locations and histologic subtypes. Positive immunoreaction for EMA was demonstrated in osteoblastic(5), chondroblastic(2), epithelioid(1), and mixed osteoblastic and fibroblastic(1) types. Osteoblastic (2), chondroblastic(2), and epithelioid(1) types among them also showed immunoreactivity with anti-simple cytokeratin monoclonal antibody, NCL-5D3. The expression of basal cytokeratin (NCL-LL002) was found in two osteoblastic, one chondroblastic, one epithelioid, and one mixed osteoblastic and fibroblastic types. These findings indicate that cytokeratin and EMA immunoreactivity can not be regarded as an absolute specific marker of the epithelial origin of tumor and may also occur in osteosarcoma.

• Keywords: Osteosarcoma;Immunohistochemistry;Cytokeratin;EMA