Primary Splenic Diffuse Large B-Cell Lymphoma With Cd30 Expression: A Rare Case Report

Primary splenic diffuse large B-cell lymphoma represents a very uncommon manifestation within the spectrum of non-Hodgkin lymphomas, comprising approximately 1% of the total caseload. We report the case of an eighty-year-old male who presented with unintentional weight loss, fever, and night sweats. Laboratory studies revealed anemia, thrombocytopenia, and elevated inflammatory markers. Imaging demonstrated splenomegaly with a large hypodense lesion, while the mediastinal and hilar lymph nodes showed only mild uptake on positron emission tomography/computed tomography, which was interpreted as indicative of inflammation. Splenectomy revealed a necrotic mass measuring 13×12×10 cm that replaced most of the splenic parenchyma. Histology showed diffuse infiltration by large atypical lymphoid cells with immunoblastic morphology. Immunohistochemistry confirmed B-cell lineage (CD20, PAX5) with negativity for CD5, BCL2, CD10, and c-MYC. The Ki-67 index was markedly elevated (95%). Importantly, the tumor also exhibited aberrant CD30 expression, a finding reported in only a minority of cases of diffuse large B-cell lymphoma. While uncommon, CD30 positivity has been suggested in the literature to carry prognostic implications and may represent a biologically distinct subset. This case emphasizes the diagnostic and clinical significance of recognizing atypical immunophenotypic features in primary splenic diffuse large B-cell lymphoma.