The accurate diagnosis of haematolymphoid malignancies is crucial for effective cancer care, but major obstacles to diagnosis exist in low- and middle-income countries (LMICs). This article explores the global applicability of current haematolymphoid classification systems, which are predominantly derived from data generated in high-income countries (HICs). Although disproportionately burdened with poor cancer outcomes, LMICs are generally faced with limited diagnostic resources, suboptimal access to therapeutics, and inadequate healthcare infrastructure. The article highlights the challenges faced by LMICs, including inconsistent access to high-quality pathology services, limited availability of advanced diagnostic techniques, and a lack of population-based cancer registry data. It also discusses the progress made in narrowing the gap between LMICs and HICs, such as the introduction of resource-adapted classifications, improved guidance on essential diagnostic tools, and strengthening of in-country professional pathology networks. Innovative diagnostic approaches, including gene expression profiling and machine learning, represent potential solutions for improving the diagnostic accuracy in LMICs, but addressable gaps remain. Recommendations are suggested for sustainable investments in diagnostic infrastructure, capacity-building, and population-based cancer registries to enhance the global applicability of haematolymphoid classification systems and improve outcomes for patients in LMICs.