Table 4.

Comparison of Pathologic Characteristics between Double-Hit Lymphoma Cases and Burkitt Lymphoma Controls

	DHL (n=20)	BL (n=25)	p-value
Light chain expression*  Absent (%)  Kappa (%)  Lambda (%)	5/18 (28) 3/18 (17) 10/18 (56)	2/13 (15) 6/13 (46) 5/13 (38)	NS
CD10 expression (%)	17/19 (89)	21/23 (91)	NS
Bcl6 expression (%)	17/19 (89)	22/24 (92)	NS
CD10 or Bcl6 expression (%)	20/20 (100)	24/24 (100)	NS
Bcl2 expression (%)	18/18# (100)	1/24^ (4)	<0.0001
Mum1 expression (%)	8/19 (42)	1/24 (4)	0.006
Ki-67 proliferation index <95% (%)	15/20 (75)	0/24 (0)	<0.0001
EBER expression (%)	0/19 (0)	8/24** (33)	0.006
Complex karyotype (3 or more abnormalities) (%)	11/11 (100)	3/6 (50)	0.03
Median number of cytogenetic abnormalities (range)	9 (5-20)	2.5 (2-6)	0.0009
MYC partner  IGH (%)  IGL (%)  Unknown (%)	0/11 (0) 9/11 (82) 2/11 (18)	5/6 (83) 1/6 (17) 0/6 (0)	0.001

^*Surface light chain expression was determined by flow cytometry in all DHL and BL cases.

^#The single DHL case that was negative for Bcl2 expression with clone 124 but positive with clone C-2 (case 3) had a t(14;18) by karyotype.

^{^}The single Bcl2+ BL case showed no BCL2 rearrangement by FISH.

^**Among 8 EBER+ BL cases, 4 arose in HIV+ adults.

BL: Burkitt lymphoma, DHL: double-hit lymphoma, EBER: Epstein-Barr virus encoded RNA, IGH: immunoglobulin heavy chain gene, IGL: immunoglobulin lambda light chain gene.