Nuclear features of infiltrating urothelial carcinoma are distinguished from low-grade noninvasive papillary urothelial carcinoma by image analysis

Abstract

Recent advances in computer technology have been made and image analysis (IA) has been introduced into pathological fields. The present study aimed to investigate the utility of IA for the evaluation of nuclear features and staining of immunohistochemistry (IHC) for Ki-67, p53 and GATA-binding protein 3 (GATA-3) in urothelial carcinoma tissue samples. A total of 49 cases of urothelial carcinoma tissue samples were obtained by transurethral resection of bladder tumors, which included 11 low-grade papillary urothelial carcinomas (LGPUCs), 1 non-invasive high-grade urothelial carcinoma and 37 infiltrating urothelial carcinomas (IUCs). Whole slide imaging (WSI) and IA were performed in Feulgen reaction and IHC-stained tissue samples. There was a significant difference in the average nuclear density, standard deviation (SD) of nuclear size and SD of nuclear minimum and maximum diameter between LGPUC and IUC, which is equivalent to the diagnostic features of IUC in nuclear variability, and hyperchromatic nuclei. In addition, the present study revealed that the SD of nuclear density was significantly different between the two groups. Regarding IA in IHC-stained tissue samples, Ki-67 was significantly overexpressed in IUC. Furthermore, the GATA-3 expression level in IUC samples with muscle invasion was significantly downregulated compared with that in non-muscle invasive tumors. The results of the present study suggest that IA in combination with WSI may be a beneficial tool for evaluating morphometric characteristics and performing semi-quantitative analysis of IHC.

Keywords: GATA-binding protein 3; Ki-67; image analysis; nuclear morphology; p53; urothelial carcinoma; whole slide imaging.

Figure 1.

Representative cases of noninvasive low-grade papillary urothelial carcinoma (case no. 24) by (A) H&E staining (magnification, ×20) and (B) Feulgen reaction (magnification, ×40); and infiltrating urothelial carcinoma (case no. 22) by (C) H&E staining (magnification, ×20) and (D) Feulgen reaction (magnification, ×40). H&E, hematoxylin and eosin.

Figure 2.

Scatter plot of nuclear parameters for Feulgen reaction tissue samples in low-grade papillary urothelial carcinoma (low-grade) and infiltrating urothelial carcinoma (infiltrating). For statistical analysis, SD of nuclear area was analyzed by Student's t-test with Welch's correction because the distribution was not homoscedastic, otherwise, the data were analyzed by Student's t-test only. Data is presented as the mean ± standard deviation. SD, standard deviation.

Figure 3.

Representative immunohistochemical staining of GATA-3, Ki-67 and p53. Low-grade papillary urothelial carcinoma (case no. 24) stained for (A) Ki-67, (B) p53 and (C) GATA-3. Infiltrating urothelial carcinoma (case no. 22) stained for (D) Ki-67, (E) p53 and (F) GATA-3. GATA-3, GATA-binding protein 3. All images were captured using a ×40 objective lens.

Figure 4.

Scatter plot of positive ratios for (A) Ki-67, (B) p53 and (C) GATA-3 in tissue samples of low-grade papillary urothelial carcinoma (low-grade) and infiltrating urothelial carcinoma (infiltrating). For statistical analysis, the data were analyzed by Student's t-test. Data is presented as the mean ± standard deviation. GATA-3, GATA-binding protein 3.

Figure 5.

ROC curve of positive ratios for (A) Ki-67, (B) p53 and (C) GATA-3. AUC value in each graph was the ratio of the area under the curve to the total area of the graph, and the points beneath the cutoff value were the points on the ROC curve with the greatest value of [sensitivity-(1-specificity)]. The dotted line is a tangent line contacted on the point and gives the greatest value parallel to the diagonal line drawn from original point in the graph in order to demonstrate the point that is the most distant point from the diagonal line. GATA-3, GATA-binding protein 3; AUC area under the curve; LGPUC, low-grade papillary urothelial carcinoma; IUC, infiltrating urothelial carcinoma; pT, pathological T factor; pT2, muscular invasion cases; pTa + pT1, non-muscle invasion cases; ROC, receiver operating characteristic.