Author: Lauren N. Stuart, M.D., M.B.A. (see Authors page)

Revised: 20 November 2015, last major update May 2013

Copyright: (c) 2002-2015,, Inc.

Definition / General
  • Expressed in all cell types; involved in chromatin remodeling and transcriptional regulation (Histopathology 2012;61:1245)
  • Also called hSNF5, SMARCB1 and BAF47
Clinical Features
Uses by Pathologists
  • Diagnosis of CNS atypical teratoid / rhabdoid tumors, renal medullary carcinoma and rhabdoid tumors (loss of expression)
  • Distinguish atypical teratoid / rhabdoid tumor (loss of INI1) from choroid plexus carcinoma (INI1+, J Neuropathol Exp Neurol 2005;64:391)
  • Differentiate epithelioid sarcoma (loss of INI1) from epithelioid hemangioendothelioma (INI1+, Am J Surg Pathol 2009;33:542)
Micro Images

Images hosted on other servers:

Composite rhabdoid tumors

Epithelioid sarcoma (INI1-)

Images hosted on

Renal medullary carcinoma

Renal rhabdoid tumor

Renal cell carcinoma with rhabdoid features (INI1+)

Orbital rhaboid tumor

Composite rhabdoid tumors

Synovial sarcoma

With rhabdoid features

CNS tumors:

Atypical teratoid / rhabdoid tumor (INI1-)

Anaplastic oligodendroglioma (INI1+)

Renal tumors:

Malignant rhabdoid tumor (INI1-)

Wilm's tumor (INI1+)

Positive Staining - Normal
  • Most normal cells
Positive Staining - Disease
  • Composite rhabdoid tumors, including rhabdoid meningioma (Mod Pathol 2005;18:951), synovial sarcoma (but reduced levels in 65%, Mod Pathol 2010;23:981)
  • Renal cell carcinoma or urothelial carcinoma, including those with histological rhabdoid features
  • Retained expression in epithelioid sarcoma-like hemangioendothelioma
Negative Staining