Cutaneous Follicle Center Lymphoma : Immunophenotype

Comments:
Immunophenotype: The neoplastic cells in cutaneous follicle center lymphoma consistently express B-cell markers (CD19, CD20, CD22, CD79a, PAX5), BCL6, and variably express CD10 (pos in follicular pattern; neg in diffuse pattern). They are negative for CD5, Cyclin D1, CD43, BCL2 (or only weakly +), immunoglobulins, IRF4/MUM1 and FOXP1. The neoplastic germinal centers have lower Ki-67 proliferation index than reactive germinal centers and do not show polarization.

If there is diffuse strong staining for BCL2, BCL6, and CD10, it should raise the concern for a systemic/nodal follicular lymphoma with secondary skin involvement.

Early lesions show prominent follicular dendritic cell meshwork with CD21 and CD35 immunostains. Cases with diffuse growth pattern usually lack this feature.