Role of genomic testing in modern diagnostic surgical pathology practice.

Genomic testing has become an essential adjunct to conventional histomorphology and immunohistochemistry in modern diagnostic surgical pathology, enabling more precise tumour classification, particularly in diagnostically challenging cases. This review focuses on the diagnostic applications of genomic techniques across multiple subspecialties, including bone and soft tissue pathology, dermatopathology, neuropathology, paediatric pathology, uropathology, and lymphoma pathology. A range of methodologies, such as fluorescence in situ hybridisation, polymerase chain reaction-based assays, and next-generation sequencing approaches (targeting DNA and RNA), are employed depending on the clinical question and the type of genomic alteration being investigated. In bone and soft tissue pathology, recurrent gene fusions, amplifications, and mutations serve as key diagnostic markers, especially in morphologically ambiguous lesions. In dermatopathology, genomic profiling plays a critical role in classifying melanocytic neoplasms, distinguishing histological mimics, and providing prognostic information. Neuropathology has pioneered integrated molecular-histological classification systems, with genomic alterations now central to the definition and grading of many central nervous system tumours. In paediatric pathology, tumours are frequently driven by structural chromosomal rearrangements and gene fusions, making RNA-based sequencing particularly valuable for diagnosis and therapeutic stratification. Similarly, molecular testing has refined the classification of renal tumours and improved the diagnostic accuracy of rare entities in uropathology. In lymphoma pathology, genomic alterations aid in distinguishing overlapping entities, confirming diagnoses, and identifying clinically significant subgroups. Emerging applications such as mutational signature analysis further enhance diagnostic precision by linking tumours to specific aetiological exposures or biological processes, which may assist in determining tumour origin in challenging cases. Despite its expanding role, genomic testing must be used judiciously and interpreted in the context of morphology, as many genetic alterations are not entirely disease-specific and assay limitations exist. Overall, the integration of genomic data with traditional pathology remains critical for accurate diagnosis, prognostication, and the advancement of precision medicine.