Adamantinoma-like Ewing's sarcoma and Ewing's-like adamantinoma. The t(11; 22), t(21; 22) status

Adamantinoma of the long bones and Ewing's sarcoma are two malignant tumours between which, at first sight, there seems to be no morphological and clinical relationship. Both tumours, however, are known to express cytokeratins. Adamantinoma is a tumour of true epithelial nature, predominantly expressing cytokeratins 14 and 19. Ewing's sarcoma, believed to be from neuroectodermal origin, like other mesenchymal tumours, can aberrantly express cytokeratin 8 and 18. In the literature there are some reports of tumours showing clinical and/or morphological overlap between adamantinoma and Ewing's sarcoma, suggesting a possible relationship. These studies are mostly based on the epithelioid configuration of these lesions and their cytokeratin expression on immunohistochemistry. This raises the question of whether there is occasionally a morphological similarity between adamantinoma and Ewing's sarcoma, or whether there is a common genetic background. The Ewing's sarcoma/primitive peripheral neuroectodermal tumour (PNET) family is characterized in 90-95% of cases by a t(11; 22) and in 5-10% of cases by t(21; 22). In the few reports in the literature on cytogenetic investigations on adamantinoma, these translocations were never found using classical karyotyping. This study investigated the putative presence of t(11; 22) and t(21; 22) in 14 cases of adamantinoma by RT-PCR. These translocations were not found in any of these cases. The results support the view that these tumours are genetically and clinically distinct, but may eventually show overlapping morphological and immunohistochemical features.