Distinct features of teratoid Wilms tumor

Teratoid Wilms tumor is an unusual variant of nephroblastoma in which heterologous tissue predominates. Typically, histopathologic examination shows a mixture of mature squamous and mucus-producing columnar epithelium and a prominent component of mature adipose tissue. The treatment of this tumor has not been established because of its rarity with some reports doubting the value of chemotherapy. We report 3 new cases and review the 23 previously reported cases that we were able to identify. The first case was a 2-year-old boy with a huge tumor that occupied most of the abdominal cavity. The second case was a 5-year-old girl with a metastatic tumor in association with horseshoe kidney and is the first case of teratoid Wilms tumor with brain metastasis. The third case was an 11-month-old girl with bilateral involvement. Imaging studies of our patients were similar to those reported in the literature with areas of fat attenuation and calcification. Failure to respond to preoperative chemotherapy was seen in our patients and in most previously reported cases that were treated with preoperative chemotherapy. We recommend treating this entity with protocols designed for Wilms tumor and to conduct further basic research to understand its biologic nature.