KIT expression in fetal, normal adult, and neoplastic renal tissues

BACKGROUND: KIT is a transmembrane tyrosine kinase receptor, expressed in high amounts in various normal cells. In addition, c-kit mutation or activation is a major pathogenetic event in certain tumours (such as gastrointestinal stromal tumours). There are only limited data in the literature on the expression of KIT in normal and neoplastic renal tissues. AIMS: To investigate KIT expression in normal and neoplastic renal tissues. METHODS: KIT expression was evaluated by means of immunohistochemistry in paraffin wax embedded sections from 67 tissue samples. RESULTS: Eight of eight fetal kidneys, and 10 of 10 normal adult kidneys revealed cytoplasmic staining of renal tubules. The three cases of renal dysplasia studied expressed KIT in their normal and aberrant tubules. Two of 13 conventional renal cell carcinomas (RCCs), two of seven papillary type RCCs, four of seven chromophobe type RCCs, none of six nephroblastomas, seven of seven oncocytomas, two of two mesoblastic nephromas, and two of four angiomyolipomas were positive. CONCLUSION: KIT is expressed in normal fetal and adult renal tubules, and in a subset of renal tumours. The expression of KIT in these renal tumours may prove to have diagnostic relevance and/or therapeutic implications.