An Unusual Progression of Follicular Lymphoma Mimicking T-Cell and Histiocyte-Rich Large B-Cell Lymphoma

A significant proportion of follicular lymphoma transform to a higher-grade lymphoma, most commonly, diffuse large B-cell lymphoma.This histologic transformation usually shows diffuse sheets of large cells; however, variant morphologic patterns are also known to occur.We report a case of a 70-year old woman who presented with an unusual large cell transformation of follicular lymphoma with a T-cell and histiocyte-rich background and limited foci of confluent large B-cells.The atypical growth pattern in the excised lymph node led to a broad differential diagnosis that not only included diffuse large B-cell lymphoma but also T-cell lymphoma and nodular lymphocyte predominant Hodgkin lymphoma.Ancillary studies confirmed a neoplastic and clonal B-cell process and immunochemotherapy was initiated.This case illustrates the need for recognition of variant morphologic patterns in large cell transformation of follicular lymphoma for appropriate classification and clinical management.