[1338] Prevalence and Prognostic Significance of 1p36 Microdeletions in Non-Hodgkin B Cell Lymphomas (B-NHL)

A Gru, F Kreisel, T Nguyen, JL Frater, A Hassan. Washington University in St. Louis, Saint Louis, MO

Background: Deletions of the chromosome 1p36 band have been described in a variety of cancers, in particular, microdeletions (mdel) have been identified in different hematologic malignancies. Diffuse follicular center cell lymphoma (FL), a low grade FL, appears to have this unifying genetic aberration. However, the prevalence and prognostic significance of 1p36mdel has not been been studied in other B-NHL, nor its prognostic significance.
Design: 47 cases of B-NHLs were retrieved from our files between 1998 -2009: 8 cases of typical low-grade FL, 7 cases of low-grade diffuse FL, 4 cases of FL vs marginal zone lymphoma (MZL), 11 cases of MZL, 7 cases of mantle cell lymphoma (MCL) and 10 cases of chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL). The diagnosis was established by morphologic analysis, flow cytometry, and immunohistochemistry. Clinical information recorded included: stage, treatment modality, survival (months), and time to recurrence. We performed FISH from formalin-fixed paraffin embedded tissue using a novel probe for 1p36mdel and 1q42. Additional FISH for t(14;18) was performed in 6 cases. Statistical analysis was perfomed using SPSS V13.0.
Results: Overall, FISH detected 1p36mdel in 86% of diffuse FL (6/7), 50% of FL vs MZL (2/4), 46% of MZL (5/11), 33% of low-grade FL (3/9), and 29% of MCL (2/7). None of the CLL had 1p36mdel. Two cases with monosomy of chromosome 1 were identified: one diffuse FL, and one MZL. The t(14;18) was positive in one low-grade FL, and one diffuse FL. The prevalence of 1p36mdel within the group was estimated as 42%. In addition the presence of 1p36mdel had significant correlation with a better survival, compared to the negative group (mean 62 vs 34 months, p=0.08). Also, independent of the histologic subtype, sex, or stage, the 1p36mdel+ group showed improved disease free survival (mean 33.3 vs 5.34 mo, p=0.02).
Conclusions: Our study indicates that 1p36mdel are highly prevalent among B-NHL, and are characteristically seen in diffuse subtype of FL, MZL, or when the distinction between FL and MZL could be challenging. It also provides a novel prognostic indicator of survival and time to recurrence of disease for these particular BNHL.


Category: Hematopathology

Wednesday, March 24, 2010 9:30 AM

Poster Session V # 173, Wednesday Morning

 

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