Clinicopathologic features of plasmablastic lymphoma: Single-center series of 8 cases from Saudi Arabia.

Background: Plasmablastic lymphoma (PBL) is a rare subtype of non-Hodgkin's lymphoma. Characterized by its aggressive nature and plasmacytic differentiation, PBL remains a therapeutic and diagnostic challenge; it generally has a poor prognosis with very few long-term survivors and most patients dying within 2 years from initial presentation. PBL has been reported in several other countries; however, there have been no reported cases from Saudi Arabia. Here, we report 8 cases of PBL depicting the clinical presentation, immunocompetency, immunphenotypic characterization, diagnostic challenges and treatment outcome.

Methods: The medical records were reviewed for clinical presentation, staging, laboratory data, radiological studies, treatments, and outcomes. A broad immunohistochemical panel consisting of CD45, CD3, CD20, CD79a, Pax5, CD38, CD138, MUM1, EMA, Kappa, Lambda, CD 56, CD30, Bcl-2, Bcl-6, Alk-1, Ki-67, EBV-LMP-1, and HHV8 was performed.

Results: The tumors predominantly exhibited immunoblastic/plasmablastic or plasmacytic morphologic features and had a plasma cell-like immunophenotype. All cases were immunoreactive for CD38, CD138 and MUM1 confirming plasma cell differentiation of the tumor cells. CD20 was negative for all cases; whereas CD79a and Pax5 were weakly positive in 2cases. All 8 cases were EBV-LMP-1/EBER-1 negative, and 1 case was HHV8 positive. Similar to previously published studies, PBL in Saudi Arabia is characterized by male predominance (6/8), median age 51.5 years (mean age 46 years), associated with early dissemination, poor response to therapy, and limited survival (average survival time, 6.4 months, median overall survival 5.5 months). However, it does have some unique features. It occurs more commonly in immunocompetent persons (6/8, 75%), is not associated with EBV infection (0/8), and nodal involvement (either primary or secondary) is common among patients (6/8). In addition, extra-oral sites are more common than oral/nasal cavities (7/8) and the c-myc gene is not common (1/8, 12.5%).

Conclusion: It appears that PBL is heterogeneous in terms of clinical presentation and morphology. PBL is a therapeutic challenge with a clinical course that is characterized by its high rate of relapse and death. To date, treatment responses are usually partial and temporary. Therapies that are more intensive than CHOP do not seem to prolong survival. Further research is needed to understand the biology and molecular pathogenesis of PBL in order to improve therapies.

Virtual Slides: The virtual slides for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1465801416161912.