Immunohistochemistry in Tumor Pathology: An Indispensable Tool for The Diagnosis and Classification of Neoplasms

Immunohistochemistry (IHC) has revolutionized diagnostic surgical pathology, evolving from a research technique to a cornerstone of modern oncologic diagnosis. By visualizing specific antigenic epitopes within the morphological context of tissue architecture, IHC provides critical information that is often unattainable by hematoxylin and eosin (H&E) staining alone. This review synthesizes the pivotal role of IHC in the verification, classification, and prognostic stratification of neoplasms. We discuss its fundamental principles, from antibody selection and antigen retrieval to signal detection and interpretation. The clinical utility of IHC is explored across major tumor types, including carcinomas, sarcomas, lymphomas, and melanocytic lesions, highlighting essential diagnostic, prognostic, and predictive biomarker panels. We address current challenges such as standardization, interpretation variability, and the integration of novel digital and multiplexing technologies. The conclusive evidence underscores IHC as an indispensable, cost-effective method that directly informs therapeutic decisions, enabling personalized cancer care within the framework of precision medicine.