Staining the Invisible: Immunohistochemistry for Early Detection of Mismatch Repair Deficiency in Pediatric High-Grade Brain Tumors

YILDIRIM Ü. M., Bilgiç B., Kebudi R.

Pediatric Blood and Cancer, vol.73, no.2, 2026 (SCI-Expanded, Scopus) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 73 Issue: 2
  • Publication Date: 2026
  • Doi Number: 10.1002/1545-5017.70084
  • Journal Name: Pediatric Blood and Cancer
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, BIOSIS, CINAHL, EMBASE, MEDLINE
  • Keywords: CMMRD, immunohistochemistry, mismatch repair deficiency, pediatric brain tumors
  • Istanbul University Affiliated: Yes

Abstract

Constitutional mismatch repair deficiency (CMMRD) is a rare autosomal recessive cancer predisposition syndrome, affecting primarily individuals from consanguineous families, leading to multiple childhood cancers, particularly high-grade central nervous system (CNS) tumors. We retrospectively analyzed 21 pediatric brain tumor samples for mismatch repair (MMR) protein expression via immunohistochemistry (IHC). One patient (4.7%) with anaplastic astrocytoma showed loss of MSH6. CMMRD was confirmed in this case via genetic testing in a sibling. IHC is a practical, low-cost screening tool, especially in resource-limited settings. Routine IHC for MMR proteins in pediatric high-grade CNS tumors may facilitate early CMMRD detection, optimize treatment, and support genetic counseling.