Immunogenetic Characterization of Non-Hodgkin Lymphoma in Iraqi Patients: Immunohistochemical Assessment of β-Catenin and Metadherin Expression with Molecular Evaluation of IgH Gene Clonality

Background: Non-Hodgkin lymphoma (NHL) is a heterogeneous category of lymphoid malignancies, defined by the disruption of major oncogenic pathways. Importantly, Wnt/β-catenin pathway activation and metadherin (MTDH) overexpression have important functions in tumor development and progression, but the patterns and interaction of these in patients in Iraq are poorly understood. There is also immunoglobulin heavy chain (IgH) gene clonality analysis which is a dependable molecular technique used to verify B-cell malignancies.

Objectives: To determine the immunohistochemical expression of β-catenin and MTDH and to determine the IgH gene clonality of Iraqi patients having NHL in order to understand its diagnostic significance and pathogenesis of the disease.

Methods: A total of 100 formalin-fixed paraffin-embedded tissue samples will be collected in the period between March and November 2025 in Baghdad Medical City and other involved centers (65 confirmed NHL cases and 35 reactive or normal controls). Immunohistochemistry was conducted to identify cytoplasmic, nuclear, and perinuclear expression of β-catenin and MTDH. Clonality of the IgH genes was determined by BIOMED-2 multiplex PCR with FR1, FR2 and FR3 regions, with the subsequent heteroduplex analysis.

Results: Cytoplasmic and perinuclear β-catenin expression was observed in 80.0% of NHL cases compared to 20.0% of controls (p < 0.001), while nuclear expression appeared in 21.5% of NHL cases and was absent in controls (p < 0.01). MTDH overexpression was detected in 64.6% of NHL samples versus 20.0% of controls (p < 0.001). Monoclonal IgH rearrangements were identified in 72.3% of NHL cases, whereas all controls showed polyclonal patterns. A significant association was found between MTDH overexpression and nuclear β-catenin expression.

Conclusion: Aberrant β-catenin activation and MTDH overexpression play key roles in NHL pathogenesis in Iraqi patients. IgH clonality analysis remains a reliable diagnostic method, and combined molecular and immunohistochemical profiling enhances diagnostic accuracy and highlights MTDH as a potential therapeutic target.