DIAGNOSIS
The correct diagnosis is C, Plasmablastic lymphoma (PBL). An incisional biopsy was undertaken and demonstrated extensive infiltration of the lamina propria with sheets of neoplastic plamablasts. Immunohistochemistry was positive for CD 138 and MUM 1 which are plasma cell markers and negative for CD 20, a mature B cell marker (Figures 2a and 2b). There was also marked positivity for Epstein-Barr virus-encoded RNA in the sample (Figure 2c). These investigations confirmed the diagnosis as Epstein Barr Virus-positive plasmablastic lymphoma, consistent with viral-induced immunosuppression
Plasmblastic lymphoma is a rare but aggressive subtype of diffuse large B-cell lymphoma (Non-Hodgkin lymphoma). It is estimated that PBL comprises 2% of HIV-related lymphoma cases. It has a male predominance (3:1), with a median age of diagnosis in HIV-positive patients of 42 years. It is strongly associated with immunodeficiency with 79 % of cases having a concomitant HIV infection and 75% having an associated EBV infection (Rodrigues-Fernandes et al., 2018). The Plasmablast is the precursor of the plasma cell and it is proposed that EBV leads to the prevention of apoptosis of these cells (Castillo et al., 2015).
The most notable feature of plasmablastic lymphoma is its predilection for the oral cavity with 66% cases presenting here. (Rodrigues-Fernandes et al., 2018) It most commonly presents as an expanding mass lesion on the gingiva or palate. Patients can also present with B symptoms: fevers, weight loss and night sweats in up to 40% of cases, however lymph node involvement is less frequently seen in these patients. (Lopez and Abrisqueta, 2018). Currently available chemotherapy fails to achieve good results and the prognosis of patients with PBL is generally poor with a median overall survival of 5–15 months (Castillo et al., 2015).