[1311] Differentiation-Associated Antigen Expression Profile of Primary Bone Diffuse Large B Cell Lymphoma (DLBCL) Analysis of 31 Cases

Q Wang, S Aisner, J Benevenia, P Patterson, K Beebe, L Pliner, M Hameed. UMDNJ-New Jersey Medical School (NJMS), Newark, NJ; UMDNJ-NJMS, Newark

Background: Primary bone lymphoma is a rare disease and comprises less than 1% of all non-Hodgkin lymphomas, with the majority being diffuse large B cell type. Because of the rarity of the disease, limited study on this entity has been done. The aim of this study is to analyze the expression profile of the prognosis-related differentiation-associated antigens.
Design: Thirty one cases of primary bone DLBCL were retrieved from UMDNJ-New Jersey Medical School from 1997-2007. Immunohistochemical staining for CD20, CD3, CD10, bcl-6, MUM-1, BCL-2, p53, Ki-67 were performed. Differentiation-associated antigen expression profile was analyzed and the cases were subclassified into two types: Germinal Center B cell (GCB) (CD10+ or CD10-/bcl-6+/MUM-1-), or non-Germinal Center B cell (non-GCB) (CD10-/bcl-6- or CD10-/bcl-6+/MUM-1+). Additional related markers such as FOXP1, HGAL, BLIMP1 are also being analyzed.
Results: The study included 19 males and 12 females with median age 44 years. The most common site was femur, followed by pelvis, humerus, tibia, fibula, radius, clavicle, and sacrum. Majority of the cases revealed a centroblastic morphology. All cases were diffusely positive for CD20. Twenty three of thirty one (74 %) cases were GCB type, of which 18 (78%) were CD10 positive, and 5 (22%) were CD10-/bcl-6+/MUM-1-. Eight of thirty one (26%) cases were non-GCB type, of which 5 (62%) were CD10-/bcl-6+/MUM-1+, and 3 (38%) were CD10-/bcl-6-. Among the 23 GCB cases, 6 (26%) were positive for p53 and 8 (34%) were positive for bcl-2, whereas in the 8 non-GCB cases, 5 (62.5%) were positive for p53 and 6 (75%) were positive for bcl-2. The mean positivity for the proliferation marker Ki-67 in GCB cases was 34.0% and that in non-GCB was 40.3%. In non-GCB lymphomas, the percentage of Ki-67 positivity was much higher in CD10-/bcl-6+/MUM-1+ (62%) than that in CD10-/bcl-6- (4%) cases.
Conclusions: In primary bone DLBCL, majority of the cases are GCB type. The non-GCB type has a higher expression of p53 and Bcl-2. The percentage of Ki-67 expression is independent of the GCB or non-GCB subtype of DLBCL. However, in non-GCB subtype, Ki-67 expression is much higher in cases with bcl-6 expression than that without bcl-6 expression.
Category: Hematopathology

Monday, March 9, 2009 9:30 AM

Poster Session I Stowell-Orbison/Autopsy Award # 193, Monday Morning