Quantitative Digital Image Analysis of MYC Immunohistochemistry in High Grade B Cell Lymphomas
Yi Xie, Casey Inouye, Lingyun Ji, Susan Groshen, Deepti Reddi, Endi Wang, Dennis O'Malley, Imran Siddiqi. LAC+USC, LA, CA; Duke University, Durham, NC; Clarient/GE, Aliso Viejo, CA
Background: Analysis of MYC gene status has emerged as an important part of the diagnostic/prognostic work-up of patients with high grade B cell lymphomas. Whereas MYC translocation is highly characteristic and diagnostic in Burkitt lymphoma (BL), it also occurs in 5% to 15% of diffuse large B cell lymphoma (DLBCL) and 35% to 50% of B cell lymphoma, unclassifiable (BCL-U) where it is associated with adverse prognosis. Recent studies report that IHC detection of MYC protein correlates with MYC translocation. Our study is the first to utilize quantitative digital image analysis to evaluate whether MYC IHC reliably predicts MYC translocation and investigate staining pattern differences in MYC translocation positive (MYC+) high grade B cell lymphomas.
Design: 6 BL, 10 BCL-U and 76 DLBCL were included in the study. FISH was performed in all cases to detect MYC translocation. The MYC IHC slides were scanned using Leica SCN400 scanner (Leica, IL) and analyzed using Slidepath image analysis software. Nuclear density algorithm was used to quantify strongly and weakly positive and negative nuclei in representative regions. The percentage of positive tumor cells was also independently scored by two pathologists.
Results: Slidepath software quantitation of total MYC IHC positive cells showed significant positive correlation with the pathologists' score (Pearson r=0.88, p<0.001). Furthermore, the percentage of MYC positive cells correlated closely with MYC translocation status. The areas under the ROC curve were 0.80 and 0.86 for software quantitation and pathologists' assessment respectively. All BL (6 of 6), 80% of BCL-U (8 of 10) and 13% of DLBCL (10 of 76) harbored MYC translocation. No significant differences were observed in the percentage of total positive cells among MYC+ BL, BCL-U and DLBCL (p=0.22). However, test of variance in the percentage of strongly positive cells showed that BL had a significantly smaller standard deviation than MYC+ DLBCL (p=0.025) and BCL-U (p=0.028), indicating that MYC overexpression in BL was more homogeneous than in MYC+ DLBCL and BCL-U.
Conclusions: Digital image analysis as a quantitative and objective measure of MYC protein expression correlates closely with the pathologists' assessment and is a useful tool to predict MYC translocation in high grade B cell lymphomas. In addition, image analysis demonstrates that MYC expression is more heterogeneous in MYC+ DLBCL and BCL-U than BL, supporting the hypothesis that MYC aberration usually occurs as a secondary event in DLBCL and BCL-U whereas it is a primary event in BL.
Monday, March 4, 2013 1:00 PM
Poster Session II # 203, Monday Afternoon