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 tumour s between which, at first sight, there seems to be no morphological and cli nical relationship. Both tumours, however. are known to express cytokeratin s. Adamantinoma is a tumour of true epithelial nature, predominantly expres sing cytokeratins 14 and 19. Ewing's sarcoma, believed to be from neuroecto dermal origin, like other mesenchymal tumours, can aberrantly express cytok eratin 8 and 18. In the literature there are some reports of tumours showin g clinical and/or morphological overlap between adamantinoma and Ewing's sa rcoma, suggesting a possible relationship. These studies are mostly based o n the epithelioid configuration of these lesions and their cytokeratin expr ession on immunohistochemistry. This raises the question of whether there i s occasionally a morphological similarity between adamantinoma and Ewing's sarcoma, or whether there is a common genetic background. The Ewing's sarco ma/primitive peripheral neuroectodermal tumour (PN ET) family is characteri zed in 90-95% of cases by a t(11; 22) and in 5-10% of cases by t(21; 22). I n the few reports in the literature on cytogenetic investigations on adaman tinoma, 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 ere not found in any of these cases. The results support the view that these tumours are gen etically and clinically distinct, but may eventually show overlapping morph ological and immunohistochemical features. Copyright (C) 2001 John Wiley & Sons, Ltd.