Clonally Related Plasmablastic Lymphoma Simultaneously Occurring with Diffuse Large B-Cell Lymphoma

Area of Science:

• Hematology
• Oncology
• Immunology

Background:

• Plasmablastic lymphoma (PBL) is an aggressive non-Hodgkin lymphoma, predominantly affecting immunocompromised individuals, but also occurring in immunocompetent patients.
• PBL is characterized by plasmacytic differentiation, lacking pan B-cell markers, with cells of origin thought to be plasmablasts.
• The pathogenesis of PBL, including the role of MYC gene alterations, remains incompletely understood.

Observation:

• A unique case of composite lymphoma involving simultaneous PBL in the urinary bladder and diffuse large B-cell lymphoma (DLBCL) in the nasal cavity is reported.
• DNA analysis of both lymphomas revealed identical immunoglobulin heavy variable gene sequences, specifically in the complementarity-determining region-3 (CDR3).
• MYC gene rearrangement was detected in the bladder PBL but not in the nasal DLBCL.

Findings:

• The identical CDR3 sequences strongly suggest that both PBL and DLBCL arose from a common clonal B-cell precursor.
• The findings support the hypothesis that PBL and DLBCL can originate from common postgerminal B cells.
• The presence of MYC rearrangement in PBL but not DLBCL in this case offers insights into potential distinct genetic events driving each component.

Implications:

• This case provides crucial evidence for a shared clonal origin of composite PBL and DLBCL, contributing to the understanding of PBL pathogenesis.
• The study highlights the importance of molecular analysis in elucidating the cellular origins and interrelationships of different lymphoma subtypes.
• Further research into the distinct genetic events and cellular pathways involved in PBL and DLBCL development is warranted.