Paraneoplastic Cushing syndrome because of corticotrophin-releasing hormone-secreting Wilms' tumor.

A 4-year-old boy with cushingoid appearance and a giant mass on his left kidney was referred to our department. Left nephroureterectomy was performed, and pathologic diagnosis was focal anaplastic nephroblastoma. Based on gradual decrease of postoperative weight, blood pressure, serum adrenocorticotropic hormone, and plasma cortisol levels, paraneoplastic Cushing syndrome because of Wilms' tumor was confirmed. Moreover, through immunohistochemical staining, we confirmed that the Wilms' tumor secreted corticotropin-releasing hormone and caused Cushing syndrome.