Diagnostic utility of Wilms′ tumour-1 protein (WT-1) immunostaining in paediatric renal tumours

Abstract

Background & objectives:Renal tumours constitute about 7 per cent of all neoplasms in children. It is important to differentiate Wilms’ tumour (commonest tumour) from non-Wilms’ tumours. The aim of this study was to evaluate the immunoexpression and diagnostic role of Wilms’ tumour-1 protein (WT1) in paediatric renal tumours.Methods:A total of 53 cases of renal tumours in children (below 18 yr) who underwent total nephrectomy were included in this retrospective study. WT1 immunostaining was done using mouse monoclonal WT1 antibody (clone: 6F-H2).Results:Of the 53 cases, 38 (72%) were of Wilms’ tumour. Non-Wilms’ group (15) included six cases of mesoblastic nephroma (MN), two each of clear cell sarcoma (CCSK), renal cell carcinoma (RCC) and peripheral neuroectodermal tumour (PNET) and one each of angiomyolipoma (AML), rhabdomyosarcoma (RMS) and malignant rhabdoid tumour (MRT). Proportion of WT1 positivity in Wilms’ tumour was 100 per cent in contrast to 26.7 per cent in non-Wilms’ tumours (P<0.001). Epithelial and blastemal components of Wilms’ tumour showed moderate (2+) nuclear and cytoplasmic staining in 80 (24/30) and 75 per cent (24/32) cases, respectively. MN, PNET, CCSK and AML were negative for WT1. RMS, RCC and MRT showed cytoplasmic staining, strongest in RMS. No significant association was seen between WT1 expression and NWTSG (National Wilms’ Tumor Study Group) stage.Interpretation & conclusions:WT1 helps to differentiate Wilms’ tumour from other paediatric renal tumours. It may help in differentiating the two subgroups of Wilms’ tumour which have distinct molecular pathogenesis and biological behaviour, however, further prospective studies are required for validation of this hypothesis.

Spectrum of round cell tumors in North -Western region of India

“…One group showed predominantly diffuse strong to moderate blastemal (75%) and epithelial (80%) positivity which was both nuclear and cytoplasmic and other group comprised eight Wilms' tumour cases with prominent heterologous elements (>50%) which showed strong cytoplasmic positivity in skeletal muscle only. 12 They found variability in the intensity of WT1 staining in the different components of the same patient and among the tumors having the same stage. 12,13…”

“…12 They found variability in the intensity of WT1 staining in the different components of the same patient and among the tumors having the same stage. 12,13…”

Retinoic acid promotes differentiation of WiT49‐ but not of CCG99‐11 Wilms tumour cells

“…WT1 is known to act during the induction of mammalian nephrogenesis, but its expression is also known to fluctuate over time during different stages of kidney development. 14,23 It is known to be expressed in Wilms tumour. 14 After 72 h RA treatment, nuclear WT1 expression became more accentuated and intense in WiT49 cells (Figure 3A,B…”

“…14,23 It is known to be expressed in Wilms tumour. 14 After 72 h RA treatment, nuclear WT1 expression became more accentuated and intense in WiT49 cells (Figure 3A,B…”

“…WT1, on the other hand, is important at several stages of nephrogenesis and nuclear expression is frequently recognised in Wilms tumour cells. 14,15 Mature epithelial tumour tubules can be highlighted by expression of specific keratins. 16 Experimentally, RA has been shown to be important in kidney development.…”