Biologically unfavorable adrenal or perirenal neuroblastoma invading the kidney may be difficult to distinguish from blastema-predominant Wilms tumor. Other tumors that enter into the differential diagnosis include Ewing Sarcoma-PNET, alveolar rhabdomyosarcoma and hematolymphoid malignancies. An immunohistochemical panel consisting of PGP9.5, MIC2 (CD99), WT-1, desmin, MyoD1, myogenin, and lymphoid markers can come to the rescue in such cases. Neuroblastoma would be diffusely positive for PGP9.5. Blastema-predominant WT is positive for vimentin and WT-1 and negative for neuroendocrine markers such as chromogranin and synaptophysin. Alveolar rhabdomyosarcoma would be positive for myoid markers and carry PAX-FKHR translocation (80% cases). EWS-PNET would show positivity for CD99 and EWS-ETS translocation. This image is of a differentiating subtype of neuroblastoma. The differentiating neuroblasts are surrounded by abundant neuropil.