Rhabdoid Differentiation in Wilms Tumor

ABSTRACT Wilms tumor (WT) is a relatively common pediatric tumor. Depending on the stage of disease, treatment includes surgery, chemotherapy, and radiotherapy. Chemotherapy and radiotherapy can induce differentiation of tumor cells to rhabdoid morphology that can masquerade as rhabdoid tumor of the kidney. We report a rare case of WT with rhabdoid differentiation subsequent to treatment with neoadjuvant chemotherapy. Rhabdoid tumor of the kidney was initially considered a sarcomatous variant of WT, however was later classified separately due to distinct behavior. This makes it challenging to differentiate from WT with rhabdoid differentiation which is important as that would also affect the aggressiveness of treatment and prognosis.