In addition, gains of chromosomes 7 and 17 and loss of Y, which are characteristic of PRCC, were observed in two cases of sPRCC and one case of MTSC, suggesting that MTSC is similar to sPRCC or may be a subtype of PRCC.
The key morphologic feature distinguishing these two is thought to be the low grade of the spindle cell areas of MTSC; spindle cell areas in PRCC generally signify sarcomatoid change and are high grade.