[Expression of cadherin17 in metanephric adenoma and its value in differential diagnosis]

To study the expression of cadherin17(CDH17) in metanephric adenoma (MA), and to explore the value of CDH17 in the diagnosis of metanephric adenoma.

Immunohistochemical EnVision method was used to detect the expression of CDH17, WT1, CD57, P504S and EMA in 21 cases of MAs, 16 epithelial-predominant Wilms tumors (e-WT), and 20 solid variant of papillary renal cell carcinomas (s-PRCC). The expression of CDH17 was also examined in other common renal epithelial tumors, including 10 cases of clear cell renal cell carcinomas (CCRCC), 10 chromophobe renal cell carcinomas (CHRCC), and 10 oncocytomas.

Twenty (95.2%) of 21 cases of MAs demonstrated membranous CDH17 immunoreactivity in all components (acinar, tubular, and papillary), whereas only 1 (1/16) e-WT was positive for CDH17 and all s-PRCCs were negative (P<0.05). WT1 was negative in s-PRCC and was positive in all cases of e-WT (16/16) and MA (100%, 21/21). All MAs (100%) were strongly positive for CD57; however, this marker was also positive in 13 (13/16) e-WTs and 9 (45.0%, 9/20) s-PRCCs. P504S was strongly positive in all s-PRCCs (100%), but reactivity was seen in 3 (14.3%, 3/21) MAs and all e-WTs were negative. The positive rates of EMA in MAs, e-WTs and s-PRCCs were 19.0%(4/21), 14/16 and 17/20, respectively. The sensitivity and specificity of CDH17 in the diagnosis of MA were 95% and 97%. CDH17 was negative in all cases of CCRCC, CHRCC and oncocytoma.

CDH17 is a highly sensitive and specific marker for MA and should be considered in the immunohistochemistry panel for distinguishing MA from its mimics and other common renal epithelial tumors.