Follicular and Mantle Cell Lymphoma Characteristics Present Simultaneously in the Same Lymph Node

Follicular lymphoma is composed of clonal germinal center B cells. It shows a follicular pattern lacking mantle zones, with a network of interfollicular dendritic cells. Transformation to more aggressive lymphomas is documented, but the only connections to mantle cell lymphoma are described cases of composite lymphoma consisting of these 2 entities. We discuss here a case of a lymph node harboring CD20+, CD10+, BCL2+, BCL6+/−, cyclin D1−, CD5+, Ki67+, and SOX11+ with CD21, showing an almost intact network of dendritic cells in one part of a lymph node, and CD20+, CD5+, SOX11+, BCL6−, cyclin D1−, CD10−, Ki67+, and CD21+ cells restricted to the mantle area in another part of the same lymph node. Both parts of the lymph node had BCL2 rearrangement, a lack of t(11:14)(q13;q32), the presence of SOX11 expression, and the same clonal band. The described case suggests heterogenous development of small cell lymphomas and indicates the possibility of differentiation regression.