The flow cytometry of peripheral blood found aberrant monocytic lineage with the following immunophenotype:

myeloperoxidase (+), CD33 (+), CD64 (+), CD14 (+), CD15 (+), CD16 (+), CD11b (+), CD36 (+), CD300e (+), CD9 (+), CD123 (+), CD34 (-), CD117 (-), CD13 (-), CD56 (+), HLA-DR (+) and CD38 (+)

Cell population included 44% promonocytes and 49% monocytes

G-banding

46,XY,t(6;22)(q23.3;q13.1)[2]/47,idem,+21[9]/46,XY[4]

As a consequence of t(6;22), the G-negative band 6q24 is translocated close to the small band q12 of chromosome 22. Between the two bands, a barely discernible G-negative region is visible, indicating that the breakpoint in the derivative chromosome 22 occurred in the subband 22q13.1. On the other hand, the translocated segment 22q13.1->22qter to chromosome 6 is too small to explain the large G-negative region that ends its long arm. Apparently, this region is composite from the G-negative region 6q23.1 – 6q23.2 and the translocated segment 22q13.1->22qter, indicating that the breakpoint in the derivative chromosome 6, respectively, occurred in the subband 6q23.3.

                                      Figure 1. G-banded karyotype showing t(6;22) (q23.3;q13.1).

                                            Figure 2. Partial G-banded karyotype showing t(6;22) (q23.3;q13.1).

Arm specific probe 6q (green) (Kreatech Diagnostic, Leica. Germany) and XCyting Chromosome Paint 22 (red) (MetaSystems, Germany).

Metaphase FISH confirmed t(6;22):

46,XY.isht(6;22)(q23.3;q13.1)(ASP6+,XCP22+; XCP22+,ASP6+)

Figure. 3 Fluorescence in situ hybridization of the long arm of chromosome 6 (green) and whole chromosome 22 (orange) demonstrating t(6;22).

The patient refused the prescribed therapy (Cytosine arabinoside, Venetoclax, Azacitidine) and was discharged from the clinic at his insistence.

The reciprocal translocation t(6;22)(q23;q13) has not been reported so far, but the breakpoints 6q23 and 22q13 are involved in multiple chromosomal rearrangements.

    In the scientific literature, 76 cases with translocations affecting 22q13 have been described found mainly in acute myeloid leukemia (AML) (60 cases): 43 cases with AML-M7, 8 cases with AML-NOS, 4 cases with AML-M4, 4 cases with AML-M5 and 1 case with AML-M2. The cases with AML-M5 had the following translocations: t(8;22)(p11;q13), t(11;22)(q23;q13) (in 2 cases with AML-M5b) and t(11;22)(q24;q13). In the later translocation KAT6A::EP300 fusion was demonstrated.

     The 6q23 breakpoint is less commonly affected. 10 cases were described, of which 9 were with acute leukemia (lymphoid and myeloid). One case with M5 and t(X;22)(p11;q13) was reported in this group. The same translocation was observed in a case with acute basophilic leukemia in which MYB-GATA1 fusion was found.

    Based on the data presented, t(6;22)(q23;q13) could be characterized as a new 22q13 variant translocation associated with AML-M5.