A Comprehensive Review of Carbohydrate Histochemical Stains and Their Diagnostic Application in Histology

Abstract

Carbohydrate histochemistry is a vital sub-discipline of histochemistry that focuses on the detection, localisation, and characterisation of carbohydrate-containing compounds such as glycogen, mucins, glycoproteins, and glycolipids within tissues. These biomolecules play fundamental roles in cellular structure, metabolism, communication, and pathological processes. Over the past ten years, carbohydrate histochemistry has continued to serve as an indispensable tool in medical histology, pathology, and biomedical research, while undergoing significant methodological refinement and expansion. This review critically synthesises research developments in carbohydrate histochemistry from the last decade, with emphasis on techniques, applications, and future prospects. The review discusses classical histochemical methods, particularly the Periodic Acid–Schiff (PAS) reaction, which remains the cornerstone technique for demonstrating glycogen, neutral mucins, basement membranes, and other polysaccharides. Modifications such as diastase-PAS and combined PAS–Alcian blue staining have enhanced specificity in differentiating carbohydrate subtypes. In addition, advances in lectin histochemistry have enabled more precise identification of specific sugar residues and glycosylation patterns at the cellular and subcellular levels. The integration of enzyme-based detection systems, digital microscopy, and image analysis has further improved sensitivity, reproducibility, and interpretative accuracy. Applications of carbohydrate histochemistry over the past decade span a wide range of biomedical fields. In pathology, altered carbohydrate expression has been associated with tumour progression, malignancy grading, metastatic potential, and inflammatory responses, underscoring its diagnostic and prognostic significance. In metabolic, renal, neurological, and infectious diseases, carbohydrate histochemical techniques have provided valuable insights into tissue alterations and disease mechanisms. The review also highlights the continued relevance of these techniques in forensic investigations and experimental research. Despite these advances, challenges remain, including variability in staining protocols, limitations in quantitative assessment, and dependence on tissue preservation and processing methods. The last decade has witnessed sustained relevance and notable progress in carbohydrate histochemistry. Continued innovation and integration with modern analytical tools are expected to further enhance its contribution to histopathology, biomedical research, and diagnostic practice.