Aims: Only a few reports on renal cell carcinoma with rhabdoid features have been published. This study was performed to investigate the clinicopathological characteristics of renal cell carcinomas with rhabdoid features.
Methods and results: Among 253 cases of renal cell carcinoma in adults, eight cases with rhabdoid features were detected. Rhabdoid areas ranged from 10% to 90% of each of the cases. Seven of the eight cases were TNM stage III or IV, and four of the eight cases died within 8 months of surgery. Immunohistochemically, the rhabdoid areas were positive for CAM 5.2 (4/8), AE1/AE3 (6/8), epithelial membrane antigen (6/8) and vimentin (8/8), and negative for myogenetic markers (0/8). The mean MIB-1 labelling index in the rhabdoid areas was higher than that in the definite carcinomatous areas. Ultrastructurally, perinuclear whorls of intermediate filaments were demonstrated in three of the eight cases using paraffin-embedded blocks.
Conclusions: The rhabdoid areas in renal cell carcinoma have histological, immunohistochemical and ultrastructural similarities to malignant rhabdoid tumours. Renal cell carcinoma with rhabdoid features is a highly aggressive neoplasm and its malignant behaviour may be due to the high cell-proliferative activity of the rhabdoid areas. Rhabdoid features in renal cell carcinoma may represent the endpoint of clonal evolution of renal cell carcinoma (especially in clear cell type cases).