Utility of CCR7 to differentiate classic Hodgkin lymphoma and other B-cell lymphomas by flow cytometry and immunohistochemistry.

Objectives: Classic Hodgkin lymphoma (CHL) is characterized by infrequent neoplastic Hodgkin and Reed-Sternberg (HRS) cells in an inflammatory background. The diagnostic utility of CC-chemokine receptor 7 (CCR7) in CHL was explored using flow cytometry and immunohistochemistry (IHC).

Methods: Neoplastic specimens and non-neoplastic lymph nodes were immunophenotyped and CCR7 expression was measured semiquantitatively by flow cytometry (clone 3D12) and IHC (clone 150503).

Results: Our results showed that CCR7 was expressed on HRS cells in the vast majority of CHL cases (45/48 by flow cytometry, 57/59 by IHC) but rarely expressed in neoplastic cells in diffuse large B-cell lymphoma, not otherwise specified (1/25 by flow cytometry, 2/40 by IHC) and nodular lymphocyte predominant Hodgkin lymphoma (0/4 by flow cytometry, 1/13 by IHC). Primary mediastinal large B-cell lymphoma (PMLBCL) revealed weak CCR7 expression by flow cytometry in most cases (8/10) but only occasionally by IHC (2/12). Both cases (2/2) of T-cell/histiocyte-rich large B-cell lymphoma (THRLBCL) also showed CCR7 expression detected by flow cytometry compared with IHC (0/7). The HRS cells demonstrated a greater percentage of positive cells and greater antigen intensity than the other B-cell lymphomas by IHC. The expression identified by flow cytometry in PMLBCL and THRLBCL but not by IHC suggests that there may be differences in the detection capabilities of the 2 techniques or the 2 CCR7 clones used.

Conclusions: The expression of CCR7 in HRS cells suggests its potential utility in differentiating CHL from other B-cell lymphomas. Incorporating CCR7 into flow cytometry and IHC panels may further enhance the diagnostic sensitivity of CHL.