Plasmablastic lymphoma

Epidemiology and Etiology:

• HIV+
• EBV+ usually
• Males predominantly
• Other immunodeficiency states
• Post-transplant
• Advanced age is a risk factor
• Median 50 y.

Common sites:

• Oral cavity
• Other extranodal

Gross features:

Histologic features:

• Large cells resembling B immunoblasts or plasma cells
• Frequent mitoses
• Less apoptotic cells and tangible body macrophages than DLBCL

Immunophenotype:

Marker:	Sensitivity:	Specificity:
EBER	60-75%	Helps distinguish from plasmablastic plasma cell myeloma
MIB1 (>90%)		Helps distinguish from plasmablastic plasma cell myeloma
CD138
CD38
Vs38c
IRF4/MUM1
CD45 (neg or weak)
CD20 (neg or weak)
PAX5 (neg or weak)
CD79a	50-85%
Ig (cytoplasmic)	50-70%
CD56 (neg usually)		Suspect underlying plasma cell myeloma if positive
EMA	Frequently
CD30	Frequently

• All cells have the immunophenotype of plasma cells

Molecular features:

• Clonal IgH gene rearrangement
• Somatic hypermutation maybe

Other features:

• May occur in setting of prior plasma cell neoplasms
• Should be distinguished from primary plasmablastic lymphoma
• Very aggressive

References:

• WHO blue book (2008)