A research report submitted to the Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree
of
Master of Medicine
in the branch of Anatomical Pathology
Johannesburg, 2016 / Introduction: Plasmablastic lymphoma (PBL) is an uncommon variant of aggressive B-cell non-Hodgkin lymphoma that occurs in immune-compromised individuals, most commonly secondary to HIV infection. This tumour classically occurs in the oral cavity but has also been described in a variety of extra-oral locations. This is a clinicopathological study of 45 cases of extra-oral PBL (EPBL).
Aim: To define the clinical parameters, histology and immunophenotypic features of extra-oral plasmablastic lymphoma (EPBL) and assess the extent to which Epstein–Barr virus (EBV) is associated with this tumour.
Materials and Methods: This retrospective study on archival cases of EPBL included the patients‟ age, gender, race, HIV status where available and the site of tumour presentation. Of 49 archival cases retrieved, 4 were discounted owing to reclassification as diffuse large B-cell lymphoma (1 case), multiple myeloma or extramedullary plasma cell tumour (3 cases). The remaining 45 cases were reviewed histologically and classified according to whether they displayed a pure plasmablastic (PBm) morphology or a plasmablastic morphology with plasmacytic differentiation (PBm+PCd), and assessed immunohistochemically with CD45 (LCA), CD20, CD79a, PAX5, CD138, MUM1, BLIMP1, VS38c, Ki-67, BCL6, CD10, HHV8 and CyclinD1 using standard automated procedures. The presence of EBV was assessed by chromogenic in-situ hybridisation. Ethical clearance was obtained (M10750 and M120993).
Results: 27of the 45 cases had a pure plasmablastic morphology. The remaining 18 cases showed plasmacytic differentiation. There was no site predilection according to histological pattern. 60% of the tumours were reported in males and 40% in females and all were black African patients. The anus was the favoured
extra-oral site of presentation (13 of 45 cases, 28%), followed by soft tissue (11 of 45 cases, 24%). There was no significant difference in the age of presentation between males (38.5 years) and females (35.4 years). Of the 18 patients of known HIV status, 17 were HIV positive (94%). The immunohistochemical profile of EPBL recapitulated that found for both oral and extra-oral PBL in the literature, except for CD45 (leucocyte common antigen) which signalled positively in a higher percentage of cases. 36 of 42 cases (85.7%) were positive for CD45. The positive membrane signal for CD45 was of variable intensity, between 5 and 100% of tumour cells. EBV was positive by in situ hybridisation in 37 of 40 cases tested (92.5%).
Conclusion: EPBL is identical to its oral counterpart in gender and age distribution, HIV status, morphological appearances, immunophenotypic profile and association with EBV. The high association with EBV as assessed by in-situ hybridisation studies mirrors that of oral-based PBL reported in the literature. EPBL should be regarded as the same tumour as that arising within the oral cavity. A peculiarity observed within this case cohort is the high level of expression of CD45 (leucocyte common antigen). This has been reported to be of low or near absent expression in most cases of PBL, as defined by the 2008 WHO Classification of Tumours of the Haematopoietic and Lymphoid Tissues. / MT2016
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/21413 |
| Date | January 2016 |
| Creators | Perner, Yvonne |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf |
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