Immunohistochemical expression of P53 protein in histologically favorable Wilms tumor and its relationship to tumor stage at presentation

ABSTRACT

Wilms tumor, as the most common renal tumor of children, has been associated with chromosomal abnormalities. Although a correlation between anaplasia and mutations of P53 tumor suppresser gene has been found in Wilms tumor, significance of these mutations in different clinical stages of favorable- Wilms tumor, remains largely unresolved. The goal of this study was to determine the frequency of P53 expression in histologically favorable Wilms tumors and its correlation to tumor-stage at presentation. In this retrospective study, 48 cases of confirmed Wilms tumor with favorable-histology were retrieved from the files of departments of pathology in three hospitals in Mashhad University of Medical Sciences between 1990 and 2004. Histological characteristics and clinicopathological staging were in accordance with National Wilms Tumor Study guidelines. P53 expression was determined by the immunohistochemical method. For each section, the proportion of neoplastic cells exhibiting nuclear positivity was broadly quantified and their intensity of staining was charted, based on visual impression by two pathologists. A total of 48 cases of histologically favorable Wilms tumor were assessed. Eleven cases [23%] showed positivity for P53 which were 3 [27.3%] with stage II, 3 [27.3%] with stage IV, 2 [18.2%] with stage I, 2 [18.2%] with stage III and 1 case [9.1%] with stage V. The P53 immunopositivity was seen in 1-25% of tumor cells in 9 cases [18.8%], in 26 to 50% of tumor cells in 1 case [2.1%] and in >75% of tumor cells in the other one case [2.1%]. The intensity of staining was moderate in 6 cases [12.5%], weak in 4 [6.3%] and strong only in one case 4.2%]. The most common component with P53 immunoreactivity was blastemal in 11 cases [100%]. In 4 cases [36.4%] there was also positivity in epithelial and in 2 cases [18.2%] in mesenchymal components. We found no correlation of P53 immunoreactivity and its intensity to tumor stage at presentation in individuals with histologyically favorable Wilms tumors [p=0.66, p=0.52 respectively]