AIDS-associated plasmablastic lymphoma presenting as a poorly differentiated esophageal tumor: A diagnostic dilemma

Table 1 Immunohistochemical findings of esophagogastric mass

Type	Antigen	Immunoreactivity
Epithelial markers	Cytokeratin 35BH11	Negative
	EMA	Diffusely positive
	BER-EP4	Negative
Lymphoid markers	CD-45	Positive
	CD-3	Negative
	CD20	Negative
	CD79a	Equivocally positive in some cells
	PAX-5	Negative
	CD30	Negative
	CD138	Positive (patchy, strong)
B-cell transcription factors	Bob-1	Positive
	Oct-2	Positive
Melanocyte markers	Melan-A	Negative
	HMB-45	Negative
	S100	Negative
Viral markers	HHV-8	Negative
	EBV (in situ hybridization)	Positive

EMA: Epithelial membrane antigen; PAX-5: Paired box gene-5; HHV-8:Human Herpes Virus type-8; EBV: Epstein Barr virus.

Table 2 Differential diagnosis of PBL

Tumor subtype	Carcinoma	PBL	Common DLBCL	BL	Plasmacytoma
Tumor cell size	Large	Large	Large	Intermediate	Intermediate
CD20	-	- to ±	+	+	-
CD45	-	Variable	+	+	-
CD138	-	+	-	-	+
VS38c	-	+	- to ±	-	+
MUM1	-	+	-	-	+
EBV	-	+	-	+	-
HHV-8	-	Variable	-	-	-

PBL: Plasmablastic lymphoma; DLBCL: Diffuse large B cell lymphoma; BL: Burkitt’s lymphoma; CD: Cluster of differentiation; MUM-1: Multiple myeloma oncogene-1-protein; EBV: Epstein Barr virus; HHV-8, human Herpes Virus type-8; +: Expression of the antigen in the majority of cells; -: Absence of antigen expression; ±: Weak antigen expression.