Splenic Small B-Cell Lymphomas (SSBCLl) of Marginal Zone (MZ) and Unclassifiable Types: A Cytogenetic (CG) and Molecular Study
SD Dufresne, RE Felgar, DW Bahler, JR Cook, U Surti, RL Sargent, SM Gollin, SH Swerdlow. U of Pittsburgh Sch. of Med., Pittsburgh, PA; U of Utah Med. Center, Salt Lake City, UT; U of Pittsburgh Grad. Sch. of Pub. Health, Pittsburgh, PA; Cleveland Clinic Foundation, Cleveland, OH
Background: Splenic MZ lymphomas (SMZL) classically have a biphasic (BP) pattern, but others have a monophasic (MP) MZ-like proliferation. The 2008 WHO also recognizes unclassifiable (UC) SSBCL. Del(7q) is the most characteristic CG marker for SMZL but is only found in a minority of cases. IGH@ mutational status also varies in SMZL and in limited studies is of prognostic value.
Design: FISH for del(7q) was performed on tissue microarrays with 43 SMZL and other UC SSBCL not of CLL, MCL, FL, or HCL type. Positive cases had 1 core with 20% positive cells. IGH@ mutation status was assessed in 17 cases. Findings were correlated with morphologic type, survival, and phenotype.
Results: The patients (med. age 66 yr, 18M:25F) had a 5 yr survival of 82%. The SSBCL included 15 SMZL-BP, 12 SMZL-MP and 16 heterogeneous UC. 16% of cases had del(7q) (2 BP, 2MP, 3UC). IGH@ was mutated in 7/17 cases (2 BP, 3 MP, 2UC). Cases with del(7q) showed some phenotypic heterogeneity but were all IGD+, CD23- and MUM1-. There was a trend for IGH@ mutated cases to be MUM1+ (p=0.13) and to have a better prognosis. 1/1 tested case with del(7q) was IGH@ unmutated.
Cytogenetic & Genotypic Correlations
|del(7q) (%)||No del(7q) (%)||Mutated (%)||Unmutated (%)|
Conclusions: Although splenic small B-cell lymphomas with del(7q) appear to be among the more phenotypically homogeneous and typical cases, they are not associated with a specific morphologic appearance. The results also suggest that some SSBCL-UC probably represent SMZL. IGH@ mutation status may have some phenotypic associations and is probably a prognostic indicator. Additional CG studies may help further clarify the spectrum of SMZL and elucidate the heterogeneous UC cases.
Monday, March 9, 2009 9:30 AM
Poster Session I Stowell-Orbison/Autopsy Award # 179, Monday Morning