Proceedings of the International scientific and practical conference ―Modern Science: Challenges and Perspectives‖ (February 9-11, 2026) / Publisher website: www.naukainfo.com. - London, United Kingdom, 2026. - 121 p.

108 histological patterns, including hyperplasia and expressed immune response that can resemble reactive changes. If CD30-positive cells predominate and exhibit characteristic features (large size, hyperchromatic nuclei), this may be indicative of Hodgkin lymphoma. In contrast, a diagnosis of lymph node hyperplasia in the absence of morphological features of neoplastic growth indicates reactive changes rather than a malignant process. The possibility of an early stage of lymphoma cannot be excluded when the clinical presentation is insufficiently expressed. When CD30-positive cells are present in small numbers among other activated lymphocytes, this finding is more consistent with reactive hyperplasia. The presence of CD30 expression in individual cells serves as a marker of B- lymphocyte activation. However, their limited number does not support a diagnosis of Hodgkin lymphoma, as classical cases are characterized by a high concentration of CD30-positive Reed–Sternberg cells. CD30 expression may be observed on activated B lymphocytes, particularly during an immune response, indicating reactive changes. In addition, CD30 is also expressed by activated T lymphocytes and by the malignant cells derived from them, including those seen in Hodgkin lymphoma. Thus, differences in approaches to histological evaluation and interpretation may lead to discrepancies in conclusions, especially in cases where the material demonstrates intermediate or atypical features. The CD30 marker is expressed on the surface of both B and T lymphocytes, which may account for variability in the interpretation of study results. Accurate interpretation requires a comprehensive approach, including analysis of histological, immunohistochemical, and molecular genetic findings. The role of EBV in the development of LPDs was confirmed by a study conducted at Texas Children’s Hospital (USA) and its affiliated medical centers between 1994 and 2018. The study included patients with persistent LAP, involvement of lymphoid organs, or lymphocytic organ infiltration lasting longer than three months, with or without chronic or significant EBV infection, in children and