FA-DLBCL is an incidental finding made by histological examination of tissues obtained at surgery conducted for reasons not related to FA-DLBCL. Microscopically, these tissues are composed of small foci of infiltrates composed of large lymphoid cells embedded in a background of<unk>  or debris. Immunohistochemistry analyses reveals that the large neoplastic cells are B-cells by their expression of B-cell marker proteins (e.g. CD20, CD30, CD45, CD79a, PAX5, and MUM1) and are infected with the EBV by their expression of this virus's proteins, e.g. EBNA2 and LMP1. Typically, these cells evidence a high rate of proliferation and are activated rather than non-activated B-cells (i.e. germinal center B-cells or unclassifiable B-cells) as identified by immunohistochemical analyses (see activated B-cells). The lesions show relatively little or no evidence of chronic inflammation except for some cases arising in pseudocysts or chronic hematomas which may show lymphoplasmacytic cells (i.e. cells with combined morphologic features of lymphocytes and plasma cells) surrounding the neoplastic B cell infiltrates. The lesions also show no evidence of tumor mass formation at the site of disease and do not extend beyond their sites of origin. Differential diagnosis FA-DLBCL-CI and (FA-DLBCL) are B-cell lymphomas. Both diseases appear driven by EBV-infected (latency stage III), large, activated B-cells and develop in spaces known or thought to be sequestered from the immune system. Unlike DLBCL-CI, FA-DLBCL is discovered as an incidental infiltrate that develops in or around sites that are not involved in chronic inflammation such as pseudocysts, cysts foreign bodies, hematomas, thrombi formed in large arteries, and myxomas. Also unlike DLBCL-CI, the lesions in FA-DLBCL do not form masses and, in almost all cases, do not extend beyond their site of origin; typically, FA-DLBCL lesions are small infiltrates composed of sheets, ribbons, or clusters of proliferating large B cells within avascular tissues that are often coated with or contain abundant<unk>  and usually have few or no other types of inflammatory cells. The disease often appears to be a non-malignant proliferation of EBV+ large B cells that are unable to survive outside of the sequestered sites: DLBCL-CI is an aggressive lymphoma with a five-year overall survival rate of 20–35% while FA-DLBCL, usually has a highly favorable outcome.
Fibrin-associated diffuse large B-cell lymphoma
Nodal marginal zone B cell lymphoma
Marginal zone B-cell lymphoma
Pediatric-type follicular lymphoma
Diffuse large B-cell lymphoma
Splenic marginal zone lymphoma
Chronic multifocal Langerhans cell histiocytosis
Epstein–Barr virus positive diffuse large B-cell lymphoma, not otherwise specified