CYTOKERATIN EXPRESSION AND DISTRIBUTION IN ADAMANTINOMA OF THE LONG BONES AND OSTEOFIBROUS DYSPLASIA OF TIBIA AND FIBULA - AN IMMUNOHISTOCHEMICAL STUDY CORRELATED TO HISTOGENESIS

Twenty-four cases of adamantinoma and 24 cases of osteofibrous dysplas ia of the long bones were studied to evaluate the expression and distr ibution of cytokeratin (CK) subtypes in relation to histogenesis and d ifferentation. The immunohistochemical study was performed on tissue f ixed in buffered formalin and embedded in paraffin wax utilizing antib odies to vimentin, factor VIII, epithelial membrane antigen and cytoke ratins of different molecular weights. In all cases the vimentin antib ody marked positively in stroma, endothelium and osteoblasts, while fa ctor VIII expression was confined to endothelial cells. In 71% of adam antinomas, vimentin showed strong immunoreactivity in the tumour cells of nests and tubules. CKAE1/AE3 and CK19 were strongly expressed in a ll morphological patterns of adamantinoma emphasizing their epithelial origin, while the antibodies to CK8 and CK18 showed a high percentage of negative responses. In osteofibrous dysplasia the epithelial-like component was much smaller than in adamantinoma and was present in sca ttered islands composed of a few cells positive for CKAE1/AE3 and CK19 and negative for other keratins. These results suggest that these two lesions are of a similar histogenesis.