Sarcomatoid renal cell carcinoma of papillary origin - A case report and cytogenetic evaluation

Sarcomatoid renal cell carcinoma (SRCC) is an aggressive tumor variant thou ght to arise predominantly from dedifferentiation of clear cell carcinoma. A few reports of SRCC associated with non-clear cell tumors led to the pres umption that SRCC may arise from any renal cell carcinoma, although direct evidence of this is lacking. Cytogenetic studies on 3 previously documented SRCCs associated with papillary renal cancers showed either 3p deletions o r absence of trisomy 7, 17 in the sarcomatoid tumors, suggesting origin fro m a coexistent clear cell tumor. The present case represents the first conc lusive evidence of direct progression of non-clear cell carcinoma to SRCC w ith both tumor components containing multiple copies of chromosomes 7 and 1 7. Many genetic anomalies, including p53 mutations, frequently recognized i n SRCC were not recognized in this case, highlighting the importance of cyt ogenetic evaluation of all SRCC. The patient is well and without evidence o f tumor progression 1 year after surgery, and the sinister outlook of SRCC in association with clear cell carcinoma may not apply in SRCC of non-clear cell origin.