B-lymphoblastic leukemia/lymphoma with cutaneous manifestations: short literature review and a rare clinical case in Kazakhstan

Background. B-lymphoblastic leukemia/lymphoma (B-ALL/LBL) is a malignant neoplasm of precursor B-cells characterized by clonal proliferation of lymphoid blasts, which by definition represent immature cells at an early stage of B-lineage differentiation. Despite shared genetic and immunophenotypic features, B-ALL and B-LBL differ in gene expression profiles, clinical presentation, and primary sites of involvement. In rare cases, extramedullary manifestations, including skin involvement, may precede bone marrow infiltration and complicate early diagnosis.

Aim. To assess the role of modern laboratory diagnostic methods in the identification of B-ALL/LBL with cutaneous involvement in Kazakhstan and their impact on patient management.

Materials and methods. Analyzed literature data and presented a clinical case of a 35‑year-old female patient with B-ALL/LBL and primary skin involvement treated at the Kazakh Research Institute of Oncology and Radiology. Laboratory investigations included complete blood count, cytological and flow cytometric immunophenotyping of bone marrow, immunohistochemical examination of a skin biopsy, conventional karyotyping, and fluorescence in situ hybridization. Instrumental studies included ultrasound examination and 18F-fluorodeoxyglucose positron emission tomography/ computed tomography. Treatment was administered according to the ALL-2022 KZ and HyperCVAD protocols.

Results. B-LBL with skin involvement are rare and difficult for diagnosis. Our patient presented with cutaneous lesions followed by bone marrow and lymph node involvement. Integrated morphological, immunophenotypic, and cytogenetic evaluation enabled timely diagnosis. Despite achieving complete remission after first-line therapy, relapse occurred and was associated with immunophenotypic changes, including altered expression of markers of immaturity and B-lineage differentiation, consistent with clonal evolution. Second-line therapy resulted in a subsequent remission, followed by autologous hematopoietic stem cell transplantation performed in Astana after referral to another specialized center.

Conclusion. Our issue demonstrates the diagnostic challenges of rare cutaneous manifestations of B-ALL/LBL and highlights the expanding role of advanced laboratory diagnostics in Kazakhstan, while emphasizing unresolved issues related to early recognition and access to comprehensive molecular profiling.