A. Low-power H&E-stained section of a lymph node involved with Burkitt lymphoma (BL) from an 82-year-old man. Note the uniform appearance of the cells, the diffuse pattern of growth, and the nuclear debris from apoptotic cells, mostly contained within the cytoplasm of pale-staining tingible-body macrophages. B. Cytology of bone marrow cells, as seen on Wright-Giemsa–stained aspirates and touch preps. Note the high nuclear-to-cytoplasmic ratio, moderately abundant dark blue cytoplasm with occasional vacuoles, and nucleus with finely granular chromatin and multiple nucleoli. C. Identification of MYC translocation by FISH analysis using “MYC break-apart probes. When together, as in a normal chromosome, the two probes are located in close proximity and give a composite yellow color, while the probes are distinct when translocation occurs (Taken with permission from Hecht and Aster³⁹). D. Composite figure from paper by Hummel et al.⁶ depicting the results of gene array studies, karyotype and FISH analyses. Top, bar graph depicting the karyotypic complexity of each case. The mBL Index section depicts a heat map of the 58 mBL signature genes; blue is low expression, while yellow is high expression. IG-myc translocations are in bright green; non-IG-myc fusions are in dark green, and myc-absent are in red. At bottom, histologic diagnosis: bright green, BL; dark green, atypical BL; red, diffuse large B-cell lymphoma (DLBCL); grey, unclassifiable mature aggressive B-cell lymphoma.