Clinicopathologic Study of 39 Mismatch Repair-deficient Sarcomas Demonstrates Recurrent Histologic Patterns and Supports Universal Screening of Pleomorphic Rhabdomyosarcoma, Uterine Leiomyosarcoma, an
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- #mismatch repair deficiency
- #sarcoma subtypes
- #immunohistochemistry screening
- The study analyzes 39 mismatch repair-deficient (dMMR) sarcomas, identifying high microsatellite instability or biallelic MMR gene inactivation.
- dMMR sarcomas are rare but enriched in pleomorphic rhabdomyosarcoma (PRMS), uterine leiomyosarcoma (LMS), and undifferentiated/unclassified pleomorphic sarcoma (UPS), with prevalence rates of 1.2% overall and higher in specific subtypes.
- Two recurrent histologic patterns in unclassified/UPS were identified: Distinctive Lobulated Inflammatory Sarcoma (DLIS) with good outcomes and a high-grade epithelioid/rhabdoid group with poorer prognosis.
- MMR deficiency in PRMS, uterine LMS, and UPS justifies universal immunohistochemistry screening for Lynch syndrome and potential immune checkpoint inhibitor therapy.
- Histologic subtyping of unclassified sarcomas predicts prognosis and treatment response, supporting tailored clinical management.