Ken's Notes

Diffuse Large B-cell Lymphoma (DLBCL)

Epidemiology:

No age restrictions

More common in elderly
Median age in 60’s

Plasmablastic:

HIV
EBV present in 60%

Common sites:

Lymph nodes
Extranodal (40%)

GI tract

Stomach
Ileocecal region
others

bone
testis
spleen
Waldeyer ring
Salivary gland
Thyroid
Liver
Kidney
Adrenal
can occur in any organ

plasmablastic:

oral cavity

Gross features:

Histologic features:

Diffuse growth pattern
large cells

nuclear size equal to or exceeding normal macrophage nuclei

or more than twice the size of a normal lymphocyte
if medium cell size, make sure to exclude extramedullary leukemias, Burkitt, and blastoid mantle cell

centroblast-like or immunoblast-like
open, heterogenous chromatin
nucleoli at margin often
variable nuclear pleomorphism
variable cytoplasm, usually moderately abundant
mixture of intermediate-sized and large cells rarely (consider intermediate BL/DLBCL)

intermixed T-cells and/or histiocytes (may be high number)
look for associated low-grade lymphoma

MALT
follicular

lymph node:

total or partial architecture effacement

partial may be interfollicular or less commonly sinusoidal

centroblastic (morphologic) variant:

medium to large cells
oval to round vesicular nuclei
fine chromatin
2-4 membrane-bound nucleoli
Multilobated nuclei maybe

Predominant in rare cases
More common in extranodal sites such as bone

Scanty amphophilic to basophilic cytoplasm
Most cases have an admixture of immunoblasts

immunoblastic (morphologic) variant:

>90% immunoblasts
Single centrally located nucleolus
Appreciable amount of basophilic cytoplasm
Plasmacytoid differentiation maybe

Anaplastic (morphologic) variant:

Large to very large
Round, oval or polygonal
Bizarre pleomorphic nuclei

May resemble Hodgkin and/or R-S cells and/or anaplastic large cell lymphoma

Sinusoidal and/or a cohesive growth pattern maybe

Mimic undifferentiated carcinoma maybe

T-cell/histiocyte rich B-cell lymphoma:
Plasmablastic:

High MIB-1 fraction (compared to plasmacytoma)
Absence of mature plasma cells

Lymphomatoid granulomatosis-type:
intravascular lymphoma:
spindle cell morphology occasionally
signet ring cell morphology occasionally
cytoplasmic granules maybe
microvillous projections maybe
intercellular junctions maybe
myxoid stroma rarely
fibrillary matrix rarely
pseudorosette formation rarely

Immunophenotype:

Marker:	Sensitivity:	Specificity:
Surface Ig (IgM > IgG > IgA)	50-75%
Cytoplasmic Ig	-/+ (CD20 negative)
CD5	10% (only rarely do these positive cases arise from CLL/SLL)	Blastoid mantle cell should be excluded by CCND1 expression
CD10	30-60%
Pan B (CD19, 20, 22, 79a) (CD20 neg in plasmablastic)	One or more may be lacking CD20 may be negative after rituximab
Bcl-6	60-85%
TdT (neg)	>95%
CD45 (neg in plasmablastic)
IRF4/MUM1	35-65%
FOXP1
CD38, CD138	(CD20 negative)
CD30	+/-
Cyclin D1 (neg)
Bcl-2	-/+
CD30	Maybe (especially anaplastic variant)
Ki67 (usually much more than 40%, commonly < 90% or heterogenous, but may be > 90% in some cases)
p53	20-60%

Immunohistochemical subgroups:

CD5-positive DLBCL:

Germinal centre B-cell-like (GCB):

CD10 in >30% of cells, OR
Bcl-6 positive AND IRF4/MUM1 negative

Non-germinal centre B-cell-like (non-GCB):

All other cases (using panel of CD10, bcl-6, IRF4/MUM1)

Note: these subgroups do not correlated exactly with gene expression-based subgrouping

Molecular features:

High Grade Lymphoma Testing Guidelines
IgH and IgL genes clonally rearranged

Somatic hypermutations in the variable regions
Ongoing IG mutations in GCB but not ABC-DLBCL

Aberrant somatic hypermutations (>50%)

Multiple loci including:

PIMI
MYC
RHOH/TTF (ARHH)
PAX5
BCL6

Translocations at 14q32 (IGH) (up to 50%)

t(14;18)(q32;q21) (IGH/BCL2) (20-30% of GCB-DLBCL)

bcl-6 rearranged (30%) and/or mutated (75%) (?better prognosis – some studies)

t(3;x)(q27;x) (20-40%)
BCL6/LAZ3 rearrangement
Promoter substitution mechanism causing deregulation of BCL6 gene

MYC rearrangement (up to 10%) (poor prognosis)

IG gene partner (60%)
t(8;14)(q24;q32) or variant (5-10%)
if concurrent IGH-BCL2 translocation and/or BCL6 translocation (20% of those with MYC rearranged)

may be better categorized as B-cell lymphoma, unclassified with features intermediate between diffuse large B-cell lymphoma and Burkitt lymphoma

If none or only a few other cytogenetic or (array) CGH abnormalities, consider BL diagnosis
If “MYC-complex” karyotype (6 or more abnormalities by array-CGH), consider intermediate BL/DLBCL

EBV (10%)

More commonly detected in DLBCL occurring in immunodeficiency

complex karyotypes

immunoblastic:

loss of 10 (whole chromosome)
8q deletion
14q deletion
4q structural abnormalities

numerical aberrations:

gains:

X, 3, 7, 12, 18

Losses:

Y, 6, 13, 15, 17

Independent of subtype:

Gains of 3p11-12 (prognostic ?pre-Retuximab)

ABC-DLBCL:

Trisomy 3
Gains:

+3q (including BCL6) (26% of ABC-DLBCL)
+18q21-22 (including MALT1 and mostly BCL2)
+19q13 (including SPIB)

Losses:

9p21 (including CDKN2A) (poor prognosis)
6q21-22

NFkB activation

GCB-DLBCL:

Gains:

1q
2p13-16 (including REL/BCL11A) (15% of GCB-DLBCL)
7
11q
12q12 (20% of GCB-DLBCL)

BCL2 rearrangement often

immunoblastic:

Gains:

1q21-25
3p24-q21
6p21
7p12-21
18q
+19q
22q12-qter

Losses:

1p35-36
2q22-24
4q32-qter
6q21-25
7q33 (survival impact - ?pre-Retuximab)
8q21 (survival impact - ?pre-Retuximab)
9p24
9q21-32
10 (whole chromosome)
11q21-qter
14q
16p13
18q21-qter

centroblastic:

Gains:

1q23-31 (poor prognosis - ?pre-Retuximab)
3q21-22
Trisomy 5 (favourable prognosis - ?pre-Retuximab)
6p
7p
7q31-32
8q22-24
11q12-13
12q14-24
18q11-21

Losses:

1p35-pter
1q (poor prognosis - ?pre-Retuximab)
2p23-pter
6q21-22
6q25-qter
8p12-pter
9p21-pter (poor prognosis)
11q23-qter
12p12-13
17p12-13 (poor prognosis)

15q “changes” (favourable prognosis - ?pre-Retuximab)
BCL2 rearrangement maybe

PMBCL:

+9/9p23-24 (minimal region of gain) (specific for PMBCL)
+2p13-16

TP53 mutation (poor prognosis)
UPD frequent
Epigenetic changes frequent
Gene expression (molecular) subgroups:

Germinal centre B-cell-like (GCB) (45-50%)
Activated B-cell-like (ABC)

Gene expression profile of activated peripheral B-cells

“Type 3” – not fitting into the above two categories
Morphology does not reliably distinguish between the molecular subgroups

Other features:

aggressive
R-CHOP therapy

rituximab has improved prognosis markedly

IPI (not as useful with rituximab):

Unfavourable variables:

Age > 60 years
Poor performance status (ECOG >= 2)
Advanced Ann Arbor stage (III-IV)
Extranodal involvement >= 2 sites
High serum LDH

BM involvement (11-27%)

BM involvement by DLBCL (concordant) – very poor prognosis
BM involvement by a low-grade B-cell lymphoma (discordant) - not prognostic
PB involvement in one third of those with BM involvement

GCB-DLBCL has better prognosis, but may have late relapses

References:

WHO Classification of Tumours of Haematopoietic and Lymphoid Organs (2008)
DakoCytomation Lymphoma Classification (2000)
Heim & Mitelman, eds. Cancer Cytogenetics, 3rd ed. (2009)
Dr. Fernandes