Cadherin-16 (CDH16) immunohistochemistry: a useful diagnostic tool for renal cell carcinoma and papillary carcinomas of the thyroid

Cadherin-16 (CDH16) plays a role in the embryonal development in kidney and thyroid. Downregulation of CDH16 RNA was found in papillary carcinomas of the thyroid. To determine the expression of CDH16 in tumors and to assess the diagnostic utility a tissue microarray containing 15,584 samples from 152 different tumor types as well as 608 samples of 76 different normal tissue types was analyzed. A membranous CDH16 immunostaining was predominantly seen in thyroid, kidney, cauda epididymis, and mesonephric remnants. In the thyroid, CDH16 staining was seen in 100% of normal samples, 86% of follicular adenomas, 60% of follicular carcinomas, but only 7% of papillary carcinomas (p < 0.0001). CDH16 positivity was frequent in nephrogenic adenomas (100%), oncocytomas (98%), chromophobe (97%), clear cell (85%), and papillary (76%) renal cell carcinomas (RCCs), various subtypes of carcinoma of the ovary (16-56%), various subtyped of carcinomas of the uterus (18-40%), as well as in various subtypes of neuroendocrine neoplasms (4-26%). Nineteen further tumor entities showed a weak to moderate CDH16 staining in up to 8% of cases. Our data suggest CDH16 as a potential diagnostic marker-as a part of a panel-for the identification of papillary carcinomas of the thyroid, nephrogenic adenomas, and the distinction of renal cell tumors from other neoplasms.