24
Lymph Nodes: Cytomorphology and Flow Cytometry
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1000m
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■ 600
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0
C
104
200
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FSC-Height
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102
103
Kappa FITC
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102
103
CD10 FITC
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CL
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a
o
CL
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D
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104T--------------------------
Kappa FI
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Lambda F
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CD5 FE
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Fig. 24.27 Mucosa-associated lymphoid tissue lymphoma.
Plasmacytoid features. (A) Papanicolaou x OI. (B) Diff-Quik x OI.
1031
1031
Fig. 24.26 Mantle cell lymphoma, flow cytometry. (A) Forward side
scatter: gated cells are small and medium in size. (B-D) Cells are almost all
lambdalight chain-restricted (red) with almost no kappa expression (blue).
(E) Moderate CD20 expression, negative CD10. (F) CD5 coexpression.
(G) FMC7 is coexpressed. (H) CD23 is not coexpressed.
D ifferential Diagnosis
L ym p hop lasm acytic ly m p h o m a is u n ifo rm ly p o sitive fo r in tra -
cytop lasm ic and surface m o n o c lo n a l IgM th a t can be easily
d em onstrated in p a ra ffin sections. These lesions are u su a lly
negative fo r C D 5, C D 10, and C D 23. T he characteristic im m u -
n op h en otyp e described fo r L P L /W M b y th e W H O classifica-
tio n , th a t is, C D 5 -, C D 10-, C D 2 3 -, is observed in 6 0 -8 0 % o f
neoplasm s, b u t va ria tio n s fro m th is p attern o f antig en expres-
s io n are c o m m o n , w ith C D 23 being detected in up to 4 0%
o f cases. A lth o u g h t(9 ;1 4 ) is stated to be present in 50% o f
cases in th e W H O m on og ra p h, tra nsloc atio ns in v o lv in g the
im m u n o g lo b u lin heavy chain in c lu d in g th e t(9 ;1 4 ) are actu-
a lly rare in L P L/W M . D e le tio n o f 6 q 21 -q 23 , a nonspecific
fi n d i n g, is th e m o st c o m m o n a b erratio n, rep orted in 4 0 -7 0 %
o f p atients.139
D istin g u ish in g L P L /W M fro m o th e r B-cell lym p hom as, espe-
c ia lly m arg inal zone B-cell lym p hom as, w h ic h share overlap-
ping m orp h olog ic features, is d iffic u lt, p a rtic ularly since the
tra d itio n a l practice o f separating L P L /W M fro m o th e r ly m p h o -
mas b y an a rb itra ry level o f serum IgM is no long er considered
v a lid .139 In filtra tio n b y m ast cells and e p ith e lio id histiocytes has
been reported, causing c on fusion eith er b y m asking the ly m -
p hom a o r sim u la tin g a T-cell lym p h o m a .140 Im m u n o p h e n o -
typ ing is im p o rta n t, since o th e r lym p h om as m ay occasionally
have lym p hop lasm acytoid features, inc lu d in g FLs (CD10+) and
693
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