Cutaneous Follicle Center Lymphoma : Differential

Comments:
Primary cutaneous follicle center lymphoma (PCFCL) vs B-cell Cutaneous Lymphoid Hyperplasia (BCLH) - Differential Diagnosis (continued).

Features favoring BCLH:

• multiple follicles with well-defined mantle zones
• polarized germinal centers showing differentiation into light and dark zones
• increased mitotic activity and high Ki-67 proliferation index
• numerous tingible body macrophages
• greater number of centroblasts and immunoblasts
• CD20+, BCL6+, BCL2-, CD10+, CD5-, and Cyclin D1-
• BCL6+ cells confined within CD21+, CD23+ follicular dendritic cell meshwork

In challenging cases where differentiation between BCLH and PCFCL is difficult, PCR can be used to examine immunoglobulin heavy chain and kappa light chain genes. The presence of a monoclonal B-cell population would favor PCFCL over BCLH. Many PCFCL cases do not have detectable levels of monoclonal B-cells by PCR. False-negative results can also occur due to suboptimal DNA quality or quantity.