Floral variant of follicular lymphoma containing marginal zone B-cell component. Report of two cases.

We here report two unusual cases of floral variant of follicular lymphoma containing marginal zone B-cells. Histologically, the neoplastic follicles consisted of three distinct layers. The inner layer was composed of neoplastic germinal centers exhibiting a floral design and the middle layer had unusually prominent mantle zones. The outer zone of neoplastic follicles was surrounded by a pale cuff of marginal zone B-cells. Immunohistological study demonstrated that both the germinal center and marginal zone component lay within the follicular dendritic cell network. The germinal center component was CD10+ and bcl-2+. However, a portion of the marginal zone component weakly expressed bcl-2 but not CD10. Nodal marginal zone B-cell lymphoma (NMZBL) occasionally possesses "floral" lymphoid follicles. Follicular lymphoma with marginal zone differentiation is a high-risk variant of follicular lymphoma. In diagnostic practice, the differential diagnosis between the floral variant of follicular lymphoma containing marginal zone B-cells and the "floral variant" of NMZBL is important.