Just for over 100 years,
adamantinoma has been recognized as a primary enigmatic bone tumour with epithelial characteristics and predominantly involving the tibia. Several similarities between
osteofibrous dysplasia has been recognised, differentiated
adamantinoma and classic
adamantinoma. The purpose of this study was to compare these lesions and to define their histogenesis and mutual relations.
METHODS AND RESULTS: Comparison of the clinical, radiologic, histological, immunohistochemical and electron microscopic findings was carried out on 6 cases of classic
adamantinoma, 2 cases of differentiated
adamantinoma and 2 cases of
osteofibrous dysplasia. This study confirmed the epithelial nature of long bone classical and differentiated
adamantinomas irrespective of their wide-ranging morphologic pattern that can mimic tumours of various origins. Both types of
adamantinoma were positive for cytokeratins in coexpression with
vimentin. The epithelial component of the differentiated
adamantinoma was much smaller than in classic
adamantinoma and was present in scattered islands or single cells distributed within fibrovascular stoma. In one case the scattered epithelial cells had abundant eosinophilic cytoplasm and they resembled rhabdoid elements. On the basis of distinct histological pattern, a new variant of differentiated
adamantinoma was described--a rhabdoid variant. In our cases of
osteofibrous dysplasia occurring in two children with
deformity of the tibia no epithelial cells were identified by the immunohistochemical methods. The lesions were composed of variably shaped spicules of woven and lamellar bone separated by a fibrovascular stroma. The woven bone spicules were surrounded by a uniform rim of plump osteoblasts. The lesion exhibited a
zonal phenomenon with maturation of woven bone to bone with a lamellar configuration at the periphery of the lesion. The similar
zonal phenomenon was also observed in the cases of differentiated
adamantinoma.
CONCLUSIONS: