Rhabdoid Tumor : INI1 Immunostain
Section Editor: Dharam M. Ramnani, MD
Virginia Urology, Richmond, VA, USA
Image Description
Immunohistochemistry: Rhabdoid tumor of kidney (RTK) shows positivity for vimentin, cytokeratin and EMA (especially in rhabdoid paranuclear inclusions). SMA, desmin, and S-100 protein are negative. Myogenin and neuroendocrine markers are sometimes expressed.
The tumor cells are characterized by loss of nuclear INI1 staining. Preservation of INI1 staining in endothelial and inflammatory cells serves as an internal positive control. Another renal neoplasm with loss of INI staining is renal medullary carcinoma. Rare cases of RTK show preservation of INI1 expression. They harbor SMARCA4 inactivation and show loss of BRG-1 nuclear staining.
Image courtesy of Dr. Jean-Christophe Fournet, Paris, France; humpath.com
The tumor cells are characterized by loss of nuclear INI1 staining. Preservation of INI1 staining in endothelial and inflammatory cells serves as an internal positive control. Another renal neoplasm with loss of INI staining is renal medullary carcinoma. Rare cases of RTK show preservation of INI1 expression. They harbor SMARCA4 inactivation and show loss of BRG-1 nuclear staining.
Image courtesy of Dr. Jean-Christophe Fournet, Paris, France; humpath.com