Northfield, Ill. (June 25, 2025)—Immunohistochemistry (IHC) can serve as a powerful surrogate for genetic testing in the diagnosis of soft tissue tumors. In a new review from the College of American Pathologists (CAP), "Immunohistochemical Surrogates of Molecular Genetic Alterations in Soft Tissue Tumors," co-authors Maria Del Carmen Rodriguez Pena, MD, FCAP, and Jason L. Hornick, MD, PhD, FCAP, detail how specific IHC markers can reliably indicate the presence of underlying genetic alterations, enabling early and accurate diagnosis, especially in challenging or resource-limited cases.
“Soft tissue tumors are rare and notoriously difficult to diagnose,” said Dr. Hornick, member of the CAP Personalized Health Care Committee. “The ability to detect molecular alterations through routine IHC is a game changer for pathologists and patients alike.”
Recent research outlines key IHC surrogates for a range of tumor types, including:
- SS18::SSX markers for synovial sarcoma
- MUC4 for low-grade fibromyxoid sarcoma and sclerosing epithelioid fibrosarcoma
- ALK and ROS1 for inflammatory myofibroblastic tumors
- DDIT3 for myxoid liposarcoma
- CAMTA1 for epithelioid hemangioendothelioma
“These markers can significantly streamline diagnosis, minimize reliance on more costly molecular techniques, and help identify candidates for targeted therapies such as tyrosine kinase inhibitors,” said Dr. Rodriguez Pena. “With high sensitivity and specificity, these markers are helping pathologists make informed decisions faster, ultimately improving patient care.”
The authors emphasize that while IHC is not a replacement for molecular testing in all cases, its utility as a rapid, cost-effective screening tool makes it indispensable in modern soft tissue pathology.
###
About the College of American Pathologists
As the world’s largest organization of board-certified pathologists and leading provider of laboratory accreditation and proficiency testing programs, the College of American Pathologists (CAP) serves patients, pathologists, and the public by fostering and advocating excellence in the practice of pathology and laboratory medicine worldwide. For more information, visit the CAP Newsroom, CAP.org and yourpathologist.org to watch pathologists at work and see the stories of the patients who trust them with their care.