INTRODUCTION
Clear cell sarcoma of the kidney (CCSK) makes up 4 % of all primary
renal malignancies in children1. Although its
prognosis has significantly improved recently1-5, the
relapse rate is still high and the prognosis of patients with relapses
is extremely poor6. Internal tandem duplication ofBCOR (BCOR -ITD)7,8,YWHAE-NUTM2B/E fusion9,10, andBCOR -CCNB3 fusion11 have been reported
in CCSK cases; however, the genetic mechanisms associated with tumor
recurrence and metastasis are still poorly understood. In this study, we
assessed the genetic mechanisms of CCSK recurrence and metastasis by
analyzing multi-sampled tumors extracted from a single case: specimens
at diagnosis, each relapse and autopsy.