[1462] Most T-Cell/Histiocyte Rich B Cell Lymphomas Express an Activated B-Cell-Like Phenotype and a Pattern of Signaling Molecules That Differ from Other Diffuse Large B-Cell Lymphomas

Y Wang, B Petersen, A Lam, I Braunschweig, J Albanese, H Ratech. Albert Einstein College of Medicine, Bronx, NY; Mount Sinai Medical School, NY, NY

Background: T-cell/histiocyte rich large B cell lymphoma (TCRBL) is an uncommon subtype of diffuse large B-cell lymphoma (DLBL) that is characterized by a predominant infiltration of reactive T- lymphocytes and histiocytes. Although clinical behavior is often aggressive, the pathogenesis of TCRBL remains largely unknown.
Design: Using tissue microarrays, we immunohistochemically stained 84 DLBL archival lymph node samples for CD10, bcl-6 protein, MUM-1, protein kinase C (PKC) β1 and β2, pTEN, and ZAP70.
Results: Among 84 DLBLs, there were 43 activated B-cell-like (ABC) and 41 germinal center B-cell-like (GC) (Table 1). Based on combined morphology and immunostaining results, we subclassified these cases into 38 DLBL-GC, 30 DLBL-ABC and 16 TCRBL. The majority of TCRBL (13/16; 81%) expressed an ABC phenotype (Chi-square, p=0.016). Furthermore, it appeared that the overall survival of patients with TCRBL was slightly better than DLBL-ABC, but worse than DLBL-GC, although this did not reach statistical significance. There were no differences in gender or age. Next, we attempted to investigate the biological basis of aggressive clinical behavior in TCRBL by studying the intrinsic signaling pathway represented by PKC β1 and β2, pTEN and ZAP 70. There were significantly more TCRBL cases (9/16; 56%) that expressed PKC β1 compared to DLBL-GC (7/38;18%) (Chi-square, p=0.040). pTEN was also more frequent in TCRBL (7/16; 43%) compared to DLBL-GC (8/38;21%) or DLBL-ABC (6/30, 20%). On the other hand, the percent of TCRBL cases (10/16; 63%) that expressed PKC β2 was intermediate between DLBL-ABC (16/30, 53%) and DLBL-GC (31/38;82%). ZAP70 showed essentially no difference among the three groups.

Table 1 Clinical and immunophenotypic data
No. of patients1668
Age, year median (range)44 (23-86)63 (4-102)
Gender F/M7/932/36
GC338* 9.93/0.016
* Chi-square test

Conclusions: The majority of TCRBL have an ABC-like phenotype and higher expression of PKC β1 and pTEN compared with other DLBLs. These findings may, in part, account for aggressive clinical behavior in some patient with TCRBL.
Category: Hematopathology

Wednesday, March 24, 2010 9:30 AM

Poster Session V # 184, Wednesday Morning


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