Thursday 1 March 2012
MYC-associated Diffuse Large B-cell Lymphoma
Determining the presence of MYC gene rearrangements is becoming an increasingly important part of the diagnostic workup in aggressive lymphoma.
Cytogenetic MYC alterations aid in differentiating diffuse large B-cell lymphoma (DLBCL) from Burkitt lymphoma.
In addition, MYC aberrations are associated with poor prognosis in DLBCL.
Fluorescence in situ hybridization and karyotyping are standard tests for detecting MYC aberrations, but these techniques are laborious and expensive.
MYC status of DLBCLs and Burkitt lymphomas can be studied using fluorescence in situ hybridization, immunohistochemistry, and quantitative real-time polymerase chain reaction (QRT-PCR).
Overall, 15% of DLBCL havve a MYC break.
QRT-PCR analysis of MYC expression shows that 72% of DLBCLs with an MYC break had aberrantly high or low levels of MYC transcript.
Excluding the cases with aberrantly low MYC expression, there is a significant positive correlation between levels of MYC transcripts and MYC tumor cells; however, QRT-PCR is not readily applicable as a screening tool.
Immunohistochemically, all tumors show a nuclear staining pattern that was simple to evaluate.
The percentage of MYC lymphoma cells correlated closely with MYC rearrangement status.
In all, 93% of cases with an MYC break had ≥80% MYC cells, in contrast to 3% of nonrearranged cases (P<0.0001).
Immunostaining for Myc protein is an excellent screening test to predict whether an MYC rearrangement is present.
High Levels of Nuclear MYC Protein Predict the Presence of MYC Rearrangement in Diffuse Large B-cell Lymphoma. Green TM, Nielsen O, de Stricker K, Xu-Monette ZY, Young KH, Møller MB. Am J Surg Pathol. 2012 Feb 3. PMID: #22314191#