CD40LG and primary cutaneous marginal zone B-cell lymphoma: Histopathologic and immunohistochemic features of pcMZL and scMZL may overlap; pcMZL generally shows IgG class-switching with polymorphous infiltrates rich in T-lymphocytes, whereas scMZL more often demonstrates IgM predominance, sheet-like B-cell infiltrates with sparse T-cells, and disrupted CD21 networks, as observed here.5