A novel three-way rearrangement involving ETV6 (12p13) and ABL1 (9q34) with an unknown partner on 3p25 resulting in a possible ETV6-ABL1 fusion in a patient with acute myeloid leukemia: a case report and a review of the literature.

BACKGROUND: Acute myeloid leukemia (AML) is commonly characterized by several chromosomal abnormalities resulting in the formation of chimeric genes that play various roles in leukemogenesis. Translocations resulting in the ETV6-ABL1 fusion gene are rare in AML and other hematologic malignancies with only thirty-two previously reported cases in the literature, five of which were AML. FINDINGS: Herein, we report the case of a 73-year-old male with acute myeloid leukemia arising from MDS, negative for PDGFRA and PDGFRB, positive for bone marrow eosinophilia, rash, and marked fluid retention, which improved dramatically with imatinib therapy. Conventional cytogenetics revealed a t(3;9)(p25;q34), t(5;18)(q13;p11.2), and additional material of unknown origin at 12p11.2 in 2 out of 10 metaphases analyzed. Interphase FISH studies showed evidence of ETV6 (12p13) and ABL1 (9q34) rearrangements in 41.3 % and 5.7 % of the cells respectively. FISH studies on previously G-banded metaphases showed colocalization of ABL1 and ETV6 signals to the short arm of chromosome 3 at 3p25 suggesting a possible ETV6-ABL1 fusion. Subtelomeric metaphase FISH studies also showed the presence of a subtelomere 3p signal on the long arm of the derivative 9, and no subtelomere 3p signal on the derivative chromosome 12. CONCLUSIONS: These findings suggest a complex rearrangement involving an insertion of ETV6 into 3p25 followed by a reciprocal translocation involving 3p25 and 9q34, resulting in a possible ETV6-ABL1 fusion. This case highlights the importance of FISH to characterize complex rearrangements in myeloid malignancies, particularly those resulting in clinically significant chimeric genes.

An Adult Male Presenting with Concurrent Plasma Cell Myeloma Involving a CCND1-IGH Translocation and Chronic Myelogenous Leukemia with a Variant (9;22) Translocation.

The t(11;14)(q13;q32) involving IGH and CCND1 a nd t(9;22) (q34;q11.2) involving BCR and ABL1 are common abnormalities in plasma cell myeloma (PCM) and chronic myelogenous leukemia (CML), respectively. However, the concurrence of the two malignancies is extremely rare. Herein, we present a case of an 87-year-old male who presented with anemia and monocytosis. FISH studies on a bone marrow sample enriched for plasma cells detected a t(11;14) positive for IGH and CCND1 fusion in 92% of nuclei. However, cytogenetic analysis of the bone marrow revealed a t(9;22)(q34;q11.2) in 40% of the metaphases. Interphase and metaphase FISH studies on the sample confirmed the presence of the BCR-ABL1 fusion in 88% of nuclei but did not show any signals corresponding to the derivative 9, suggesting a variant t(9;22) with a deletion or additional material of unknown origin at the 9q34 band of the derivative 9 and a derivative 22 bearing the BCR-ABL1 fusion gene. The concurrence of plasma cell myeloma and chronic myelogenous leukemia is extremely rare with less than 20 cases reported. The molecular pathway in which the multiple malignancies arise is still poorly understood, and this case provides insight into the concurrence of PCM and CML.