Cavity-based lymphomas: challenges and novel concepts. A report of the 2022 EA4HP/SH lymphoma workshop

Abstract

The 2022 European Association for Haematopathology/Society for Hematopathology lymphoma workshop session on cavity-based lymphomas included sixty-eight cases in seven sections. The disease entities discussed include primary effusion lymphomas (PEL), extracavitary primary effusion lymphomas and confounding entities (ECPEL), HHV8-negative B-lineage lymphomas-effusion based (EBV-negative, EBV-positive, and plasmablastic types), diffuse large B-cell lymphoma associated with chronic inflammation, fibrin-associated diffuse large B-cell lymphoma (FA-DLBCL), breast implant-associated anaplastic large cell lymphoma (BIA-ALCL), and other lymphomas presenting as an effusion. All entities above are discussed; however, three are delved into greater detail given the challenges with classification: ECPEL, HHV8-negative effusion-based lymphomas, and FA-DLBCL. Cases exemplifying the diagnostic difficulty in differentiating ECPEL from HHV8-positive diffuse large B-cell lymphoma and germinotropic lymphoproliferative disorder were discussed. The more recently recognized effusion-based HHV8-negative large B-cell lymphoma is explored, with several cases submitted raising the question if this subset should be carved out as a specific entity, and if so, what should be the refining diagnostic criteria. Case submissions to the FA-DLBCL section yielded one of the largest case series to date, including classic cases, cases furthering the discussion on disease sites and prognosis, as well as novel concepts to be considered in this entity. The 2022 EA4HP/SH workshop cases allowed for further confirmation of the characteristics of some of the more historically accepted cavity-based lymphomas, as well as further inquiry and debate on relatively new or evolving entities.

Polymorphic lymphoproliferative disorder arising in a rheumatoid arthritis patient, presenting as fibrin‐associated large B‐cell lymphoma‐like lesions in aortic and mitral valves

“…Histologically, it shows aggregates of large lymphoid cells which are surrounded by fibrin and cellular debris, without infiltration into pre‐existing normal tissue or mass formation 8 . The tumor cells typically express activated B‐cell‐like type and usually demonstrate latency type III EBV infection 11 . In our case, the histology and immunophenotype of large lymphoid cells arising on heart valves resembled FA‐LBCL.…”

“…Therefore, we expect that our patient would have better prognosis for her MTX‐LPDs as she was aged <70 years. The most cases of FA‐LBCL are reported to have excellent outcomes 11 . The first choice of treatment of MTX‐LPD is discontinuation of MTX, and if relapse or remission is not achieved, chemotherapy is indicated.…”

Fibrin-associated large B-cell lymphoma arising in an endovascular graft: first case report in Korea

“…Since the description of this entity is relatively recent, the overall incidence remains unclear. Approximately 50 to 60 cases of FA-LBCL have been reported in the English literature [ 1 – 7 ], and it has been described in cases throughout the body at sites of chronic fibrin deposition, including in the walls of pseudocysts (splenic, renal, adrenal, paratesticular, and ovarian teratomas), hydroceles, chronic subdural and testicular hematomas, breast implant capsules, materials located in the cardiovascular system (cardiac myxoma, cardiac prosthesis, cardiac fibrinous thrombus, and synthetic vascular grafts), and wear debris associated with metallic implants [ 1 – 7 ]. Although these lesions have been described in distinct locations, the histology is remarkably similar to atypical B cells embedded in a fibrinous background.…”

“…Therefore, it was recently described as a fibrinassociated large B-cell lymphoma (FA-LBCL) in the novel fifth edition of the WHO classification as an unusual form of LBCL [ 2 ]. Approximately 50 to 60 cases of FA-LBCL have been reported in the English literature, and it has been described in cases throughout the body at sites of chronic fibrin deposition [ 1 – 7 ].…”

The Possible Role of Pathogens and Chronic Immune Stimulation in the Development of Diffuse Large B-Cell Lymphoma

“…It is the primary cause of Kaposi sarcoma, often called the Kaposi sarcoma herpesvirus (KSHV). In the WHO 2002 classification, there are three separate entities for HHV8-associated DLBCL: the primary effusion lymphoma, the KSHV/HHV8 positive diffuse large B-cell lymphoma, and the KSHV/HHV8 germinotropic lymphoproliferative disorder [ 1 , 18 , 72 ]. HHV8-positive DLBCL (NOS) is mainly seen after the multicentric Castleman disease [ 72 ].…”