• Clear cell renal cell carcinoma;
  • tumour heterogeneity;
  • prognosis

The aim of this study was to define the histological spectrum, frequency and significance of nonconventional tumour cells in clear cell renal cell carcinomas (CCRCC). Fifty-one totally sampled CCRCC were studied histologically to evaluate the spectrum of cell morphology variability, its frequency and significance, and their correlation with tumour grade and stage, and other histological parameters of aggressive behaviour like necrosis. Aside from conventional clear/eosinophilic granular cells, three additional cellular types were identified and considered in this study: small clear cells, syncytial cells and rhabdoid cells. Small clear cells were detected in 11 cases (21.5%), syncytial cells in 8 (15.6%) and rhabdoid cells in 5 (9.8%). The presence of syncytial and rhabdoid cells statistically correlated with grade (p = 0.003 and p = 0.006) and stage (p = 0.049 and p = 0.05) in CCRCC. Necrosis correlated with stage (p = 0.018) and grade (p = 0.004), but not with syncytial, rhabdoid or small clear cells. The presence of syncytial and rhabdoid cells in CCRCC is a relatively frequent event that significantly correlates with high-grade tumours and high stage status.