Applications of Immunohistochemistry in Disease Diagnosis: Principles, Challenges, and Recent Advances

Abstract

Immunohistochemistry (IHC) is a fundamental diagnostic technique that allows the detection and localisation of specific antigens within tissue sections through antigen–antibody interactions. Immunohistochemistry has developed into a vital tool in laboratory medicine and diagnostic pathology by fusing molecular specificity with retained tissue morphology. It is frequently used in the diagnosis, categorization, and prognosis of a wide range of illnesses, such as autoimmune, inflammatory, infectious, and neoplastic diseases. The sensitivity and dependability of immunohistochemical assays have been significantly improved by developments in staining techniques, detecting systems, and antibody creation. IHC aids in the classification of tumours, the identification of the tissue of origin, and the assessment of prognostic and predictive biomarkers in clinical practice, thereby enhancing diagnostic precision and therapeutic decision-making. Immunohistochemistry is widely used; however, staining results can be affected by a number of technical and interpretive issues. Variability can be introduced by pre-analytical factors, such as tissue fixation and processing, as well as analytical factors like antibody selection, antigen retrieval, and detection techniques. Additionally, there are still many difficulties with standardization, quality assurance, and result interpretation, especially in laboratory settings with limited resources. This narrative review discusses the fundamental principles of immunohistochemistry, its major applications in disease diagnosis, and the common technical and interpretative challenges encountered in routine practice. Additionally highlighted are recent developments in immunohistochemical methods, such as automation, multiplex staining, and digital pathology.