Myogenin and Desmin Immunohistochemistry in the Assessment of Post-Chemotherapy Genitourinary Embryonal Rhabdomyosarcoma: Prognostic and Management Implications

The significance of undifferentiated myogenin/desmin positive cells in genitourinary embryonal rhabdomyosarcoma in the absence of morphological residual/recurrent embryonal rhabdomyosarcoma remains unclear since such cells can be detected in all cases of posttreatment embryonal rhabdomyosarcoma. In some cases findings are associated with clinical disease recurrence, while others with identical histopathological findings following initial treatment have no clinical sequelae even in the absence of further treatment. In genitourinary embryonal rhabdomyosarcoma close and regular clinical surveillance is essential. Desmin/myogenin immunohistochemistry to detect scattered undifferentiated cells does not appear to provide useful prognostic information.