Genomic inactivation and loss of nuclear expression of SMARCB1, a core subunit of the SWItch Sucrose Non-Fermentable (SWI/SNF) chromatin remodeling complex, characterizes a plethora of mesenchymal neoplasms with, overall, diverse histopathologic appearance and biologic properties [30, 31]. The gene discussed is SMARCB1; the disease is mesenchymal cell neoplasm.