[1451] DRC Patterns in Follicular Lymphoma Correlates with Response to Rituxan Therapy

S Tatishchev, R Dewar. Beth Israel Deaconess Medical Center & Harvard Medical School, Boston, MA

Background: Histological grading and morphology in follicular lymphoma (FL) correlate poorly with clinical outcome, especially in this era of Rituxan therapy. With the hypothesis that follicular micro-environment is important for disease dissemination and response of B-cells to Rituxan, we studied dendritic reticular cell (DRC) patterns in FL.
Design: 25 cases including 20 FL & 5 other small B-NHL controls were retrieved from archives. All FLs were predominantly (>75%) follicular. Mean follow-up 28 months (m); range 12-120 m. Morphology/IHC were correlated with clinical stage & response to Rituxan. The architecture of DRC (CD21/23) in 5 random neoplastic nodules/case was evaluated by image analysis (NIH Image). Based on DRC architecture, FL cases fell into 3 categories: (a) expanded DRC (n=10): DRC meshwork occupied 75-100% of nodule:

(b) disrupted DRC (n=8): DRC meshwork was involuted, B-cells overgrew DRC (<25% of nodule): (c) DRC meshwork was scant to absent within defined nodules (n=2).

Results: No differences was seen within groups for Ki-67, grade or demographics; also cases with absent DRC (n=2) & controls (n=5) did not show differences. Significant differences existed between expanded & disrupted DRC groups: (a) Expanded DRC meshworks were present in early lesions (mean:25m; range:12-60 m). Disrupted DRC meshworks were seen at late stages (36 months; 24-120 m). (b) Expanded DRCs were seen in localized disease (33%) compared to disrupted DRCs (12%). Among those requiring Rituxan based therapy (R-CHOP or R-CVP) response (regression of nodes by imaging) to Rituxan based therapy was seen more in expanded DRC group (Chi-square statistic; ϒ²=7.7; 0.01Conclusions: B-cell localization within expanded DRC in FL seems to correlate with early disease, clinical stage & response to Rituxan based therapy.
Category: Hematopathology

Monday, March 22, 2010 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 193, Monday Morning


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