Grading of renal cell carcinoma

Abstract

Grading of renal cell carcinoma (RCC) has been recognised as a prognostic factor for almost 100 years. Numerous grading systems have been proposed, initially focusing upon a constellation of cytological features and more recently on nuclear morphology. It has been recommended that grading of RCC should be based upon nucleolar prominence/eosinophilia for grades 1–3, while grade 4 requires nuclear anaplasia (including tumour giant cells, sarcomatoid differentiation and/or rhabdoid morphology). The grading system was adopted formally by the International Society of Urological Pathology (ISUP) and subsequently by the World Health Organisation (WHO), being designated the WHO/ISUP grading classification in the fourth edition of the WHO classification tumours of the urinary system and male genital organs (2016). This grading system has been validated for both clear cell and papillary RCC. Validation studies for chromophobe RCC failed to demonstrate a correlation between grade and outcome for both the superseded Fuhrman grading system and the WHO/ISUP grading classification, and it has been recommended that these tumours not be graded. The WHO/ISUP system has been incorporated into the structured reports of the International Cancer Collaboration on Cancer Reporting for both clear cell and papillary RCC. It is also noted that other types of RCC may be graded, but it must be emphasised in the report that this is for descriptive and diagnostic purposes, and not outcome prediction. More recent studies have shown the incorporation of the presence of tumour necrosis into RCC grading to improve outcome prediction, and this has been validated in several studies.

Impact of sarcomatoid differentiation and rhabdoid differentiation on prognosis for renal cell carcinoma with vena caval tumour thrombus treated surgically

“…RCC with sarcomatoid differentiation is classified as grade 4 by the WHO/ISUP grading system [11]. However, grade 4 RCC with sarcomatoid differentiation has significantly worse CSS than grade 4 RCC without differentiation [10,18].…”

“…Gökden et al [9] reported an incidence of rhabdoid differentiation of 4.7% and revealed associations between rhabdoid differentiation and increased grade and stage for the first time. Delahunt et al [11] reviewed previous studies that reported survivals ranging from 8 to 31 months. In a more recent study of grade 4 RCC, 45 [18].…”

“…Rhabdoid differentiation in RCC is considered a predictor of poor prognosis, similar to sarcomatoid differentiation. Therefore, the World Health Organization International Society of Urological Pathology (WHO/ISUP) grading system formally classifies RCC with either sarcomatoid differentiation or rhabdoid differentiation as grade 4 [11]. The impact of rhabdoid differentiation in RCC on prognosis has been studied to some extent, but the available reports have inconsistent conclusions.…”

Updates in Staging and Reporting of Genitourinary Malignancies

“…76 The World Health Organization/International Society of Urologic Pathology nucleolar grade is now used in place of the Fuhrman nuclear grade. 1,19,77,78 This grading system is based on nucleolar prominence for grades 1 through 3, whereas grade 4 consists of more aggressive rhabdoid, sarcomatoid, and anaplastic morphologies. 1,19,77,78 The World Health Organization/International Society of Urologic Pathology nucleolar grade correlates with prognosis in both clear cell and papillary renal cell carcinoma, but not with chromophobe renal cell carcinoma, and the latter should not be graded.…”

Chromophobe Renal Cell Carcinoma Aggressiveness and Immuno-oncology Therapy: How to Distinguish the Good One from the Bad One

“…However, its clinical significance could not be demonstrated for chRCC, because prominent nucleoli are not frequent in chRCC. Therefore, it was recommended that chRCC should not be graded [2,[7][8][9].…”