Adamantinoma of long bones: clinical, pathological and ultrastructural features

The clinical, pathological and ultrastructural features of two cases of tibial adamantinoma are described. Both lesions showed identical features with a mixed histological picture exhibiting baseloid, tubular and squamous differentiation and a prominent stromal (mesenchymal) component. By light microscopy there appeared to be an intimate relation between the epithelial and mesenchymal components. By electromicroscopy the cellular constituents of these components could be readily distinguished. In the former the cells contained tonofilaments and desmosomes which were associated with basement membrane material. In the latter (mesenchymal component) none of these features was notes, instead the cells appeared similar to fibroblasts and occasional myofibroblasts.