Figure 2.

Representative metaphase fluorescence in situ hybridization in ALK-positive large B-cell lymphoma; magnification, ×1,000). The hybridization targets of the orange color probes and the green color probes are on opposite sides the breakpoint of the ALK gene. A two-color signal would represent a fusion signal in patients with native ALK, but they became two separated signals (one orange and one green) in this patient with ALK break-apart pattern. In addition, extra (>2) copies of the ALK gene in single cell were also observed. ALK, anaplastic lymphoma kinase.