Which molecular and cytogenetic findings are characteristic of sarcomatoid renal cell carcinoma (SRCC)?

Updated: Mar 11, 2019
  • Author: Ronald J Cohen, MB, BCh, PhD, FRCPA, FFPATH; Chief Editor: Liang Cheng, MD  more...
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Little information is available on genetic alterations in SRCC. Mutations of the p53 tumor suppressor gene are reported to be more prevalent in sarcomatoid components (79%) compared with clear cell components (14%) of SRCC arising from CCRCC. [50]

Cytogenetic analysis of 6 tumors with predominant sarcomatoid components has revealed complex polyploid karyotypes in 5 (83%) cases, [51] which is consistent with the view that sarcomatoid differentiation represents an advanced (late) step in the progression of RCC. This is supported by findings of polyploid DNA indices in the sarcomatoid components of 8 SRCCs, compared with hypodiploid or hyperdiploid DNA indices in the RCC components. [39]

Similarly, genetic analysis by fluorescent in situ hybridization has shown polyploidy of chromosomes 1, 2, 6, 10, and 17 in the sarcomatoid components of 6 chromophobe RCCs, whereas the RCC components had either 1 (monosomy) or 2 (disomy) copies of these chromosomes. [40] In rare cases, cytogenetic analysis has shown alterations involving chromosome 3p in SRCC associated with CCRCC [52] or polysomy of chromosomes 7 and 17 in SRCC associated with papillary RCC. [53]

However, in most cases analyzed, SRCC does not show the underlying chromosomal changes that are characteristic of the histologic type of RCC it is derived from, suggesting that sarcomatoid change occurs more frequently in a subgroup of tumors that are genetically atypical. [40, 51]

A study by Ito et al found that sarcomatoid differentiation in RCC is associated with a high rate of chromosomal imbalances with losses of 9q, 15q, 18p/q and 22q, and gains of 1q and 8q occurring at significantly higher frequencies in comparison to non-sRCC tumors. [54]

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