J. de Bie MD, PhD

Current advances in cytogenomics – Implementation of Optical Genome Mapping into diagnostic workflows for haematological neoplasms: A Belgian Cytogenomic Group for Haemato-Oncology (BCG-HO) position statement

SUMMARY

Genomic abnormalities play an increasingly important role in prognostication and classification of haematological malignancies (HM), as evidenced by their continual integration into updated classification and risk assessment models. Optical Genome Mapping (OGM) is a relatively new high-resolution technology that offers novel opportunities to assess chromosome abnormalities, increasing the detection yield of clinically relevant abnormalities and allowing rationalisation of diagnostic pathways by abrogating the need for multiple complementary tests. Furthermore, it could streamline laboratory’s technical pipelines, avoiding the need for multiple disease specific workflows. Given these findings, OGM is currently being implemented into the diagnostic workflow, as a first line test, by numerous laboratories worldwide and is being validated with view to implementation in many more, including Belgium. Here we propose recommendations for implementation of OGM testing in the routine diagnostic workup of HM.

(BELG J HEMATOL 2024;15(6):233–7)

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Diagnosis of a gamma heavy chain disease in a 71-year-old patient with a persistent leukopenia and thrombocytopenia

SUMMARY

A 71-year-old man with persistent leukopenia and thrombocytopenia was referred to the haematology department with a suspicion of a myelodysplastic neoplasm (MDS). Upon presentation, the patient was asymptomatic. Peripheral blood analysis confirmed leukopenia and thrombocytopenia. Furthermore, IgG was elevated, while IgM, total protein and the kappa-lambda free light chain (FLC) ratio were within normal ranges. Protein electrophoresis pattern showed a prominent monoclonal peak in the gamma globulin region. The monoclonal peak was identified as IgG heavy chain without corresponding kappa or lambda light chains by immunofixation analysis. Bone marrow cytology did not provide evidence for MDS; however, an increased plasmocytosis of 8% was detected. Immunophenotyping showed the presence of 6.6% CD19+, CD38++, CD138+, CD45+ and CD56- plasma cells without cytoplasmic light chain expression. The latter was confirmed by histologic review of the bone marrow biopsy using immunohistochemical staining. Immunoglobin gene rearrangement analysis was indicative for the presence of a monoclonal B-cell or plasma cell neoplasm. On positron emission tomography (PET)-scan only a mild splenomegaly was seen. Based on all these results, the diagnosis of a gamma heavy chain disease (gHCD) was made. As the patient was asymptomatic, treatment was not indicated. Blood count and health status were unchanged at a check-up six months later. Further follow-up is performed every six months. This case report presents the diagnostic work-up of a patient with gHCD. Laboratory analysis contributing to the diagnosis of gHCD included protein electrophoresis, immunofixation, bone marrow cytology, immunophenotyping, molecular analysis and pathological examinations of a bone biopsy.

(BELG J HEMATOL 2024;15(2):49–53)

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P06 Targeted single cell sequencing unravels the heterogeneity of human T-cell acute lymphoblastic leukemia samples

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