Pathologic findings and histologic grading of LYG. Histologic grading of LYG is based on the number and density of EBV⁺ atypical B cells and degree of coagulative necrosis. Low-grade (grades 1 and 2) disease is characterized by sparse EBER⁺ atypical B cells, as well as focal or absent coagulative necrosis. An increased number and size of EBER⁺ atypical B cells are seen in high-grade (grade 3) disease with often-extensive coagulative necrosis. A reactive angiocentric and angiodestructive CD3⁺ T-cell infiltrate is another characteristic pathologic feature across all grades of the disease. An increased frequency of monoclonality by molecular analysis is seen with higher grades of disease, likely representative of the progressive transformation of EBV-infected B cells.