Fig. 2

The results of a diagnostic work-up of a patient with CRLF2-rearranged BCR::ABL1-like ALL which occurred during a relapse after a prolonged remission despite the absence of CRLF2 rearrangement at the initial diagnosis. Top left side: FISH analysis with CRLF2 break-apart probe (CytoCell®) on leukemic blasts at the initial diagnosis. In the normal cell, 2 fused red/green signals (2 R/G) or 2 yellow signals (2Y) are observed. Top right side: FISH analysis with CRLF2 break-apart probe (CytoCell®) on leukemic blasts at the relapse after prolonged remission (13 years). A translocation resulting in 1R, 1G, 1R/G. Bottom: Second step analysis with IGH probe (CytoCell®). In a normal cell, 2 fused red/green signals (2 R/G) or 2 yellow signals (2Y) are expected. Cells with 1R, 1G, 1R/G are indicative of IGH rearrangement. ALL, acute lymphoblastic leukemia; CRLF2, cytokine receptor-like factor 2; FISH, fluorescent in-situ hybridization