NLPHL : CD21

Comments:
Nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL): The nodules in NLPHL are composed of CD20+ and IgD+ B-cells, reactive T-cells, and expanded, loose meshwork of follicular dendritic cells which can be best visualized with CD21 immunostain. The nodules are variable in size but generally larger than those seen in follicular lymphoma and lack a mantle zone. Foci with diffuse growth may be seen. In rare cases, the diffuse growth pattern predominates.

Lymphocyte-predominant (LP) cells are found within the follicular dendritic cell networks. Most LP cells are surrounded by T cells expressing CD3 (see image), CD4, and CD57. The CD4+ T cells express PD1 and IRF4 (MUM1).

The presence of T-cell rosettes around CD20+, BCL6+ LP cells is a useful diagnostic feature of NLPHL and helps distinguish it from progressively transformed germinal centers, mixed cellularity Hodgkin lymphoma, and T cell/histiocyte-rich B cell lymphoma.