In Situ Follicular Lymphoma Developed after Hodgkin Lymphoma

ABSTRACT

In situ follicular lymphoma is a newly defined entity among the lymphoid neoplasms and is defined as architecturally normal-appearing lymph nodes and other lymphoid tissues that have one or more follicles that demonstrate bcl-2 overexpressing centrocytes and centroblasts, with or without a monomorphic cytologic appearance suggestive of follicular lymphoma. Here we present a case of in situ follicular lymphoma diagnosed during the follow-up after a complete response to the treatment of lymphocyte-rich classical Hodgkin's lymphoma. In our case, because only a few germinal centers contained bcl-2 overexpressing cells, we missed the diagnosis of in situ follicular lymphoma in the initial histological examination. We could establish the diagnosis only after performing bcl-2 immunostaining in the sequential biopsy. Therefore, we recommend that careful histological examination along with bcl-2 immunostaining is needed in patients with suspicious clinical findings.