Plasmablastic lymphoma (PBL) is a type of large B-cell lymphoma recognized by the World Health Organization (WHO) in 2017 as belonging to a subgroup of lymphomas termed lymphoid neoplasms with plasmablastic differentiation. The other lymphoid neoplasms within this subgroup are: plasmablastic plasma cell lymphoma (or the plasmacytoma variant of this disease); primary effusion lymphoma that is Kaposi's sarcoma-associated herpesvirus positive or Kaposi's sarcoma-associated Herpesvirus negative; anaplastic lymphoma kinase-positive large B-cell lymphoma; and human herpesvirus 8-positive diffuse large B-cell lymphoma, not otherwise specified. All of these lymphomas are malignancies of plasmablasts, i.e. B-cells that have differentiated into plasmablasts but because of their malignant nature: fail to differentiate further into mature plasma cells; proliferate excessively; and accumulate in and injure various tissues and organs. The lymphomas in the lymphoid neoplasms with plasmablastic differentiation sub-group that are not PBL have sometimes been incorrectly considered to be variants of PBL. Each of the lymphomas in this subgroup of malignancies have distinctive clinical, morphological, and abnormal gene features. However, key features of these lymphomas sometime overlap with other lymphomas including those that are in this sub-group. In consequence, correctly diagnosing these lymphomas has been challenging. Nonetheless, it is particularly important to diagnose them correctly because they can have very different prognoses and treatments than the lymphomas which they resemble. Plasmablastic lymphomas are aggressive and rare malignancies that usually respond poorly to chemotherapy and carry a very poor prognosis. They occur predominantly in males who have HIV/AIDS, had a solid organ transplant, or are immunosuppressed in other ways; ~5% of all individuals with PBL appear to be immunocompetent, i.e. to have no apparent defect in their immune system. The malignant plasmablasts in more than half the cases of PBL are infected with a potentially cancer-causing virus, Epstein–Barr virus (EBV), and rare cases of PBL appear due to the plasmablastic transformation of a preexisting low-grade B-cell lymphoma. One variant of PBL, sometimes termed plasmablastic lymphoma of the elderly, has a significantly better prognosis than most other cases of PBL. The development of this variant appears due, at least in part, to immunosenescence, i.e. the immunodeficiency occurring in old age.
Presentation Plasmablastic lymphoma lesions are most commonly rapidly growing, soft tissue masses that may be ulcerating, bleeding, and/or painful. In a recent (2020) review of published cases, individuals presenting with PBL were typically middle-aged or elderly (range 1–88 years; median age 58 tears) males (~73% of cases). Only a few cases have been reported in pediatric cases. The PBL lesions occurred most commonly in lymph nodes (~23% of cases), the gastrointestinal tract (~18%), bone marrow (16%), and oral cavity (12%). Less frequently involved tissues include the skin, genitourinary tract, paranasal sinuses, lung, and bones. While cases of PBL may present as a primary oral, or, very rarely a skin or lymph node disease, most individuals present with a widespread stage III or IV disease which in ~40% of cases, is accompanied by systemic B-symptoms such as fever, night sweats, and recent weight loss. Some 48%-63% of PBL cases occur in individuals with HIV/AIDS; ~80% of these HIV/AIDS-afflicted individuals have EBV+ disease whereas only ~50% of PBL individuals that do not have HIV/AIDS are EBV-positive. Individuals with PBL often present with a history of being immunosuppressed due to prior organ transplantation, immunosuppressive drug treatment, or other causes. This is particularly the case for individuals with HIV/AIDS-negative disease. Individuals who develop PBL following organ transplantation are EBV/AIDS-positive in >85% of cases. Most post-transplant and HIV/AIDS-positive patients have an extremely aggressive disease. However, patients whose major contributing factor to PBL-development is EBV-positivity often present with, and continue to have, a significantly less aggressive disease than other patients with PBL. It is similarly clear that, on average, individuals who are elderly (>68 years) or have HIV/AIDS-negative disease likewise present with, and continue to have, a significantly less aggressive cancer.
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