Recent molecular characterization of neoplasms previously designated as SCU HBs has resulted in the reclassification of many of these tumors as rhabdoid tumors given the associated loss of SMARCB1 expression [7,8] resulting from underlying loss-of-function variants or deletions in the SMARCB1 gene, sometimes constitutional, characteristic of this group of neoplasms. The gene discussed is SMARCB1; the disease is rhabdoid tumor.