B-cell Lymphoma of Large Multilobated Type: An Immunohistochemical Study of 8 Cases and Review of the Literature

Large multilobated cell lymphomas represent an heterogenous group comprising both B-cell and T-cell subtypes. The correct lineage identification of each subtype cannot be based on morphologic grounds, as it has already been stressed by other authors, and demands the use of immunophenotyping methods. In this study we review the literature and present eight new cases of large multilobated B-cell lymphoma which have been immunophenotyped in paraffin sections with a panel of monoclonal [L26 (CD20), 4KB5 (CD45R), UCHLl (CD45RO), MT1 (CD43)] and polyclonal (anti-CD3, anti-k, anti-λ) antibodies. We further investigated the expression of c-myc p62 oncoprotein and of proliferating cell nuclear antigen (PCNA) using the monoclonal antibodies c-myc 1-9E10 and PC-10 respectively. In all cases the neoplastic cells were positive for L26 (CD20) and negative for anti-CD3. Five cases were positive for 4KB5 (CD45R) while six cases stained positively for UCHLl (CD45RO) or MT1 (CD43). Four cases were monoclonal in respect to light chain restriction. Immunoreactivity with c-myc 1-9E10 and PC-10 was observed in all cases. As far as c-myc 1-9E10 is concerned, positive cells constituted more than 45% of the neoplastic population in six cases, whereas in all cases the percentage of PC-10 positive cells was greater than 45%. The staining pattern was nuclear and/or cytoplasmic for c-myc 1-9E10 but solely nuclear for PC-10. The elevated c-myc and PCNA expression are indices of high proliferation rate in this type of lymphoma and may suggest a high malignancy grade.