Desmoplastic small round cell tumour of the pleura:a case report with further cytogenetic andultrastructural evidence of «mesothelioblastemic» origin

A typical case of desmoplastic small round cell tumour of the pleura in a 25-year-old man is described. In addition to the typical histological and immunohistological findings, the EWS-WT1 fusion product was also observed. Ultrastructurally, some tumour cells displayed intracytoplasmic neolumina, with short microvilli characteristic of submesothelial cells. These findings support the theory of a splanchnopleuric intraembryonic mesodermal, «mesothelioblastemic» origin, both morphologically and cytogenetically.