Vladimír Bartoš1, Juraj Mikuláš2, Roman Mráz2
Aim: Currently, a novel 4-tiered grading system for clear cell renal cell carcinoma (RCC) has been proposed, that in addition to ‘classic’ criteria of nucleolar prominence derived from Fuhrman scheme also includes a presence/absence of tumour necrosis. In the present study we compared the differences between those two classification systems in the set of conventional clear cell RCCs. Material and methods: Study group consisted of 145 representative clear cell RCCs from 145 patients (87 men, 58 women) in the age range between 31-82 years. The biopsy samples were routinely processed and evaluated in the light microscope. Results: According to ‘classic’ 4-tiered scheme of nuclear differentiation, the most frequent was grade II (n = 59; 40.7 %), followed by grade I and III in the same number (n = 31; 21.4 %) and the least common was grade IV (n = 24; 16.5 %). Necroses were found in 44 cases (30.3 %) and their incidence was increasing with declining of tumour differentiation. After re-classification according to novel 4-tiered scheme incorporating necrosis, the most frequent was grade I (n = 86; 59.3 %) followed by grade III (n = 22; 15.2 %), grade IV (n = 21; 14.5 %) and grade II (n = 16; 11.0 %). Among all tumours, 75 cases (51.7 %) ‘persisted’ at the same grade level after re-classification. In the remaining cases, there was a one grade ‘shift’ down (in 3 cases from original grade IV into grade III, in 12 cases from grade III into grade II, and in 55 cases from grade II into grade I). There was a significant increase of grade I (from original 21.4 % to 59.3 %), while a percentage of all other grades, most markedly grade II (from original 40.7 % to 11.0 %) was reduced. Conclusion: To confirm a higher efficacy of this novel system or to recommend it in routine practice, a precise follow-up of larger number of patients would be necessary. Anyway, one of its advantages is that an integration of tumour necrosis into the grading system as a one of the crucial criteria ‘highlights’ their prognostic impact in overall clinical context, but this also requires their targeted searching during biopsy examination.