SALL4 Expression in Urothelial Carcinoma of Urinary Bladder; a Tissue Microarray Analysis

Sal-like protein 4 (SALL4) is a cellular pluripotent embryonic nuclear factor that has been a useful immunohistochemistry marker for germ-cell tumors. Our understanding of SALL4 expression in other human body malignancies remains limited. The diagnostic value of SALL4 expression as an independent diagnostic marker for patients with bladder urothelial carcinoma remains unclear. The aim of this study is to investigate the relation of SALL4 immunostaining in urinary bladder urothelial carcinoma and normal bladder urothelial tissue with clinicopathological diagnostic parameters. Material and methods: Three hundred and seventy cases of bladder urothelial carcinomas and 22 non-neoplastic bladder urothelial tissues were obtained from the Department of Pathology at King Abdulaziz University Jeddah, Saudi Arabia. Tissue microarrays were constructed. Tissue sections were stained using anti-human SALL4 monoclonal antibody. The immunostaining results were recorded and analyzed. Results: SALL4 exhibited weak nuclear expression in only 6 out of 370 cases of bladder urothelial carcinomas (1.6%). All the SALL4-positive cases were high-grade tumors. Normal urothelial tissues were all completely negative. SALL4 immunostaining revealed no association with gender, age, tumor invasiveness, stage, lymphovascular invasion, regional lymph node metastasis, or distant metastasis. Conclusion: SALL4 is rarely expressed in bladder urothelial carcinoma and is typically limited to high-grade tumors. However, this immunoexpression must be kept in mind when applying SALL4 antibody for differentiating urothelial carcinomas from germ-cell tumors and when assessing metastatic poorly differentiated tumors of unknown origin.