[1375] Gray Zone Lymphomas: Becoming More Black and White?

Thomas A Summers, Franziska C Eberle, Stefania Pittaluga, Wyndham H Wilson, Kieron Dunleavy, Mark Raffeld, Stephen M Hewitt, Elaine S Jaffe. National Cancer Institute, NIH, Bethesda, MD

Background: The 4th Edition of the WHO Classification of Tumours of the Haematopoietic and Lymphoid Tissues includes borderline categories for cases that do not fit into one entity, allowing for well-defined groups to remain homogenous and further study of the borderline cases. One such category is the B-cell lymphoma, unclassifiable, with features intermediate between diffuse large B-cell lymphoma (DLBCL) and classical Hodgkin lymphoma (CHL), i.e. “gray zone lymphoma” (GZL). Most GZLs present with a mediastinal mass, and share features with nodular sclerosis CHL and primary mediastinal large B-cell lymphoma (PMBL). p63 has been shown to be absent in Hodgkin/Reed-Sternberg (HRS) cells, while variably expressed in other lymphomas. Conversely, Cyclin E has been reported as absent in PMBL and present in HRS cells.
Design: We evaluated the expression of p63 and Cyclin E in a well-defined population of mediastinal GZL (N=29) utilizing a tissue microarray (TMA) analysis. 14/29 cases were morphologically more suggestive of CHL, while 15/29 cases were more suggestive of PMBL. Five-micron TMA sections were prepared for immunophenotypic analysis according to the standard avidin-biotin complex method. Positive expression for both markers was defined as greater than 20% nuclear staining within the cells of interest.
Results: Cyclin E was positive in 23/29 (79%); (Figure 1) p63 was positive in 14/29 (48%) of cases.

Analyzed according to morphological subsets, 64% (9/14) and 43% (6/14) of CHL-like tumors (A) expressed Cyclin E and p63 respectively. 93% (14/15) and 53% (8/15) of PMBL-like tumors (B) expressed Cyclin E and p63 respectively.
Conclusions: p63 and Cyclin E do not help to differentiate gray zone lymphomas into more well-defined diagnostic categories, such as CHL or PMBL. These data add to other genetic and epigenetic data that characterize MGZL as a distinct entity distinguishable from both CHL and PMBL.
Category: Hematopathology

Wednesday, March 2, 2011 1:00 PM

Poster Session VI # 206, Wednesday Afternoon


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