[1567] Angioimmunoblastic T-Cell Lymphoma with Hyperplastic Germinal Centres (Pattern 1) Assumes Conventional, Geographic, Floral and Progressively Transformed Variants Unified by Superior Survival, Unassociated with Secondary B-Lineage Lymphomas, Compared to Patterns 2 and 3 — A Meta-Analysis of 56 Cases

Leonard HC Tan, Soo Y Tan, Tiffany Tang, Soon T Lim, Daryl CL Tan. Singapore General Hospital, Singapore; National Cancer Centre, Singapore

Background: Angioimmunoblastic T-cell lymphoma (AITL) may be subclassified into Patterns (P) 1, 2 and 3, indicating hyperplastic, regressed and effaced germinal centres (GCs) respectively, but the prognostic utility thereof has not been validated.
Design: 25 cases of AITL were reviewed immunohistologically and with in-situ hybridisation for EBV-encoded RNA and PCR for TCRγ and IGH clonality, and followed up to 120 months. Data were compared and merged with those from Attygalle et al, who had follow up to 247 months (AJSP 2007;31:1077). Gender, stage, nodal presentation, CD10+, EBV+, clonality and survival (Fig A) rates were similar in both cohorts. Mean ages (65 vs 57 years respectively) were not significantly different (p=0.1081).


Results: Our cohort had 7 P1 [2 each with conventional, geographic and floral hyperplastic, and 1 with progressively transformed (PT) GCs], 1 P2 and 17 P3 cases. P1 cases had superior 5-year survival (5ys 83% vs 36% in P2/P3, p=0.0417) only when combined with the 31 cases of Attygalle et al, 7 of which were P1; yet TCRγ clonality rates were similar (93% P1 vs 94% P2/P3). Of discordantly diagnosed (DD) cases (n=17), 15 were mistaken as "reactive", 9 of which were P1 (64% of n=14), compared to only 8 DD (6 called “reactive” and 1 each “Hodgkin” and “marginal zone lymphomas”) P2/P3 cases (19% of n=42, p=0.0024). Significant survival separation (p=0.0203) was also found between DD (81% 5ys) vs concordantly diagnosed (31% 5ys, n=39) patients (superimposed on P1 vs P2/P3 in Fig B, overall p=0.0211). Secondary B-lineage (classical Hodgkin or diffuse large cell) lymphoma (BLL) was associated exclusively with Pattern 3 (p=0.0057).
Conclusions: P1 represents an indolent phase/grade of AITL, often mistaken histologically for a reactive process, unassociated with secondary BLL, and uninfluenced by treatment regimen. P1 variants include those with geographic, hitherto-undescribed floral, and PTGCs.
Category: Hematopathology

Wednesday, March 21, 2012 9:30 AM

Poster Session V # 195, Wednesday Morning

 

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