Plasmablastic Lymphoma : CD138
The immunophenotypic profile of plasmablastic lymphoma is similar to plasma cells. They are negative for CD45 and show absent or weak expression of pan B-cell markers (CD20, CD79a, and PAX5). They are positive for plasma cell-associated markers (CD38, CD138, IRF4/MUM-1 and VS38c), with variable expression of immunoglobulins. BCL6 is negative or only focally positive. Ki67 proliferation index is high (usually >90%). EBV is positive in 75% of cases. HHV8 is negative. The image shows strong immunoreactivity for CD138 in a plasmablastic lymphoma arising in the oral cavity of a young HIV+ male (same case as the previous three images).