Indolent lymphoplasmacytic and marginal zone B-cell lymphomas: absence of both IRF4 and Ki67 expression identifies a better prognosis subgroup.
OBJECTIVE
Small B-cell indolent lymphomas postulated to be of a post-germinal center origin include marginal zone lymphomas of the spleen (S-MZL) or lymph nodes (N-MZL) and mucosa-associated lymphoid tissue (MALT) lymphomas and lymphoplasmacytic lymphomas (LPL). The existence of rather aggressive cases stresses the need for new biological prognostic markers.


METHODS
We analyzed 90 tumors (20 LPL, 41 MALT lymphomas, 12 N-MZL, 17 S-MZL), investigating the expression of CD5, CD10, CD20, CD23, CD27, CD38, CD79a, CD138, Bcl6, cyclin D1, IRF4 and Ki67 antigens by immunohistochemistry. Results were compared to the histology, the standard clinical and biological parameters, and the global survival.


RESULTS
Tumors were all positive for CD20 and CD79a, occasionally positive for CD5, CD23, CD138 and cyclin D1, and all negative for Bcl-6 and CD10. CD38, CD27 and IRF4 expression was heterogeneous. IRF4 expression was correlated with plasma-cell differentiation (p=0.0017). Ki67 expression was increased mainly in N-MZL (66%) and LPL (45%). In terms of overall survival, Ki67, IRF4 and C-reactive protein levels were found to be the 3 independent parameters associated with a worse outcome. Lack of both Ki67 and IRF4 expression was associated with a longer survival (median overall survival 9.8+/-1.1 years versus 3.6+/-1.3 years in the other group) (p=0.0011).


CONCLUSIONS
Absence of expression of both Ki67 and IRF4 is likely to define a group of memory B-cell lymphomas with a better prognosis. This may have an important impact in the staging of patients since expression of these markers is easily assessed in routine diagnosis.
Petit
Barbara
B
Laboratoire d'Anatomie Pathologique, France.
Chaury
Marie-Pierre
MP
Le Clorennec
Christophe
C
Jaccard
Arnaud
A
Gachard
Nathalie
N
Moalic-Judge
Sandra
S
Labrousse
François
F
Cogné
Michel
M
Bordessoule
Dominique
D
Feuillard
Jean
J
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007150:Immunohistochemistry; D050835:Interferon Regulatory Factors / Q000096:biosynthesis*; D019394:Ki-67 Antigen / Q000096:biosynthesis*; D008223:Lymphoma / Q000175:diagnosis / Q000378:metabolism*; D016393:Lymphoma, B-Cell / Q000175:diagnosis / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012189:Retrospective Studies; D013997:Time Factors; D016896:Treatment Outcome; D000099218:Interferon Regulatory Factor-4
D050835:Interferon Regulatory Factors; D019394:Ki-67 Antigen; D000099218:Interferon Regulatory Factor-4