Which immunohistochemical findings are characteristic of rhabdoid renal cell carcinoma (RRCC)?

Updated: Mar 11, 2019
  • Author: Ronald J Cohen, MB, BCh, PhD, FRCPA, FFPATH; Chief Editor: Liang Cheng, MD  more...
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Immunoreactivity for epithelial markers is common in the rhabdoid components of RRCC, providing evidence of their epithelial derivation. Rhabdoid cells have positive staining for cytokeratin cocktail AE1/AE3 in 58-75% of cases and for epithelial membrane antigen in 41-78% of cases, while the intermediate filament vimentin is expressed in 100% of cases arising from clear cell, papillary, or collecting duct RCC.

Both cytokeratin and vimentin give diffuse cytoplasmic staining with strong accentuation in the globular cytoplasmic inclusion bodies. [8, 10, 11] Vimentin staining was negative in both components of the single reported case of RRCC arising from chromophobe RCC, consistent with the fact that chromophobe RCCs do not express vimentin. [9] Despite their morphology, the rhabdoid cells show no evidence of myoblastic differentiation, as immunostains for the muscle markers desmin and muscle-specific actin/smooth muscle actin are negative. [8, 10, 11]

Nuclear staining for the Ki-67 nuclear proliferation antigen is significantly stronger in rhabdoid components compared with RCC components, consistent with the aggressive behavior associated with rhabdoid change. [10] Rhabdoid components of RRCC also more frequently show overexpression of mutant p53 tumor suppressor protein compared with the RCC components. [11]

The rhabdoid component of RRCC closely resembles pediatric MRT of the kidney in all aspects, including histologic appearance, immunohistochemical profile, and ultrastructural details. [8, 37] However, the median age at diagnosis for renal MRT is 11 months, with a range of newborn to 9 years, [37] and 84% of MRT tumors have lost expression of the hSNF5/INI protein due to genetic alterations involving chromosome 22. [46, 47, 48]

For RRCC, hSNF5/INI is expressed in the rhabdoid components, [49] and extensive sampling reveals a coexisting RCC component in most cases. [48] Identification of a typical RCC component also helps distinguish RRCC from other renal tumors that may contain rhabdoid elements, including transitional cell carcinoma and rhabdomyosarcoma. [8, 37] In the case of rhabdomyosarcoma, the malignant rhabdomyoblast cells can be differentiated by positive expression of at least one muscle marker-most commonly, desmin, myoglobin, or muscle-specific actin. [43]

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