Primary Diffuse Large B-Cell Lymphoma of the Urinary Bladder: Update on a Rare Disease and Potential Diagnostic Pitfalls

Abstract

Diffuse large B-cell lymphoma (DLBCL) represents the most frequent type of non-Hodgkin lymphoma. Globally, DLBCL is an aggressive disease, requiring an accurate diagnosis and prompt treatment. The diagnosis is often made on biopsy samples of a nodal mass, however, approximately 40% of DLBCL cases arise at extranodal sites. The most common extranodal site is the gastrointestinal tract, however any extranodal area may be primarily involved. Primary urinary bladder lymphoma represents only 0.2% of extranodal non-Hodgkin lymphomas, whereas secondary involvement of the urinary bladder by a systemic lymphoma is a more common event. Despite being rare, DLBCL is considered to represent the predominant primary urinary bladder lymphoma. The majority of cases reported in the bladder belong to the DLBCL, NOS group, and there are only rare cases of EBV-positive DLBCL, NOS. In this review, we summarize the current knowledge on DLBCL primarily occurring in the urinary bladder, with the aim of increasing clinician and pathologist awareness on this aggressive lymphoma rarely arising in the urinary bladder. Additionally, we focus on those entities which should be taken into consideration in the differential diagnosis, highlighting potential diagnostic pitfalls.

A Rare Case of Diffuse Large B-Cell Lymphoma Found in the Subcutaneous Scalp

“…Of all forms of DLBCL, extranodal forms only comprise 34.48% [10]. The gastrointestinal tract has been noted to be the most common extranodal site [8]. Although, any extranodal site could be the site of primary involvement [8].…”

“…Rare sites of extranodal DLBCL have been documented in the literature, including presentations in the scalp, testicles, bone, bladder, and nasal septum [2][3][6][7][8][9]. A recent 2022 study found that the percentages of extranodal DLBCL from years 2000-2015 at the age of 18 or greater in their search were as follows: GI tract 28.31%, nervous system 13.78%, head and neck 11.79%, skin and soft tissue 9.54%, genitourinary 7.24%, musculoskeletal 5.80%, respiratory tract 5.17%, pancreas and hepatobiliary 4.16%, endocrine organs 3.66%, heart and mediastinum 3.28%, breast 2.49%, bone marrow 2.47%, and others 2.30% [10].…”

“…Diffuse large b-cell lymphoma (DLBCL) represents approximately one-third of all non-Hodgkin's lymphomas [1]; extranodal presentation on the scalp is rare [2][3]. Rare extranodal presentations documented in the literature include the scalp, testicles, bone, bladder, and nasal septum, whereas, the gastrointestinal tract is the most common extranodal site [2][3][4][5][6][7][8][9]. Skin involvement in DLBCL can occur as a primary or secondary manifestation, which can be difficult to differentiate [1,4].…”

Programmed Death Ligand 1 (PD-L1) Expression in Lymphomas: State of the Art

“…DLBCL, named large B-cell lymphoma (LBCL) in the recent WHO classification, is a broad and very heterogeneous category, including entities with distinct clinicopathological and biological characteristics. It may involve lymph nodes as well as extra-nodal sites [ 47 , 48 , 49 ]. The definition of diffuse large B-cell lymphoma not otherwise specified (DLBCL, NOS) is used for cases not belonging to any specific variant of DLBCL.…”