FISH is Still an Excellent Tool to Monitor High-Grade Lymphomas.

Objectives: A 61-year-old male patient whose core needle biopsies of tissue involved a malignant lymphoid infiltrate composed of intermediate to large cells positive for CD20, PAX5, CD10, BCL6, BCL2, and cMYC, and negative for MUM1. Mitotic activity was brisk with a correspondingly high index of proliferation by Ki67 (~95%) and the patient was diagnosed with a diffuse large B-cell lymphoma, germinal center phenotype. DNA FISH analysis was performed on the paraffin embedded tissue from the right external iliac lymph node using the LSI BCL6 (3q27) and MYC (8q24) dual color break apart probes from Cytocell and the LSI BCL2 (18q21) dual color break apart probe from Abbott. We found rearrangements of BCL6 in 95% of the cells examined, MYC rearrangements in 77% of the cells and BCL2 rearrangements in 95% of the nuclei. These findings allowed us to classify this case as a triple-hit lymphoma now called "high-grade B-cell lymphomas" with MYC, BCL2, and/or BCL6 rearrangements.