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Published on: September 1, 2010
Pathology and diagnosis of SMARCB1-deficient tumors
Ashley S Margol1, Alexander R Judkins2
1Children's Hospital Los Angeles, Los Angeles, CA, USA; Department of Pediatrics, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA.
Abstract:
Malignant rhabdoid tumor (MRT) can occur in the kidney, central nervous system, or extracranial/extrarenal locations and is characterized by alterations in the SMARCB1 gene. The tumors occur in infants and young children and confer a poor prognosis requiring aggressive therapeutic interventions to improve the chances for survival. MRTs pose a diagnostic challenge, as they display heterogeneous histopathologic features and differentiate along multiple lineages. The identification of alterations in the SMARCB1 gene in MRT using immunohistochemical (IHC) staining has lead to improved diagnosis of MRT as well as the discovery of the loss of SMARCB1 expression in some non-MRTs. Whether loss of SMARCB1 plays a pathogenic role in nonrhabdoid tumors remains to be determined; however, most of these tumors lack the clinical and other molecular features of MRT. We review the histopathologic features of MRT and the importance and significance of loss of expression of SMARCB1 in both MRT and nonrhabdoid tumors.
Insights
Malignant rhabdoid tumors (MRT) in children are aggressive and hard to diagnose. SMARCB1 gene alterations are key, and immunohistochemical staining aids diagnosis, revealing SMARCB1 loss in some non-MRT cases.
Area of Science:
- Pediatric Oncology
- Molecular Pathology
- Genetics
Background:
- Malignant rhabdoid tumor (MRT) is an aggressive pediatric cancer found in various locations.
- Characterized by SMARCB1 gene alterations, MRT presents diagnostic challenges due to heterogeneous histopathology.
- Early diagnosis and aggressive treatment are crucial for improving survival rates in affected infants and young children.
Purpose of the Study:
- To review the histopathologic features of MRT.
- To highlight the diagnostic significance of SMARCB1 gene alterations.
- To discuss the role of SMARCB1 loss in both MRT and nonrhabdoid tumors.
Main Methods:
- Review of histopathologic features of MRT.
- Analysis of immunohistochemical (IHC) staining for SMARCB1 expression.
- Correlation of SMARCB1 alterations with clinical and molecular features.
Main Results:
- SMARCB1 gene alterations are characteristic of MRT.
- IHC staining for SMARCB1 improves MRT diagnosis.
- Loss of SMARCB1 expression is observed in some non-MRTs, though its pathogenic role is under investigation.
Conclusions:
- SMARCB1 alterations are critical for MRT diagnosis and understanding.
- IHC is a valuable tool for identifying SMARCB1 loss.
- Further research is needed to determine the role of SMARCB1 loss in nonrhabdoid tumors.
