Follicular hodgkin lymphoma: a histopathologic study.

Follicular Hodgkin lymphoma (FHL) is a form of classic Hodgkin lymphoma with morphologic similarity to nodular lymphocyte predominant Hodgkin lymphoma (NLPHL). We present the clinicopathologic features of 13 FHL cases and compare their morphologic features with 40 cases of NLPHL. Seven males and 6 females had FHL in the lymph nodes of the neck (6 patients), axilla (3 patients), groin (2 patients), and mediastinum (1 patient) and in the nasopharynx (1 patient). All FHLs had follicles with small, eccentric germinal centers (GCs) and expanded mantle zones containing classic Reed-Sternberg (RS) cells; reactive GCs also were seen in 6 of 13 cases. The RS cells were CD30+, fascin+ in 13 cases; CD15+ in 11 cases; CD20+ in 4 cases; CD79alpha+CD20- in 1 case; and negative for epithelial membrane antigen in 12 cases; they were surrounded by CD3epsilon+ and CD57+ rosettes in 13 and 2 cases, respectively. Morphologically, FHL may closely simulate NLPHL, and, thus, immunohistochemical analysis is essential to confirm the diagnosis. Clues helpful in diagnosing FHL include the presence offollicles with GCs, classic RS cells, and a relative absence of histiocytes.