Inv(16)(p13q22)
Inversions of chromosome 16 and rearrangements involving band 16q22 are almost exclusively observed in acute nonlymphocytic leukemia, specifically acute myelomonocytic leukemia (AMMoL:FAB-M4eo). This chromosome abnormality is associated with increased numbers of immature eosinophils in the bone marrow and peripheral blood. Eosinophils may show some nuclear hypo-segmentation and positive PAS/PE staining. These patients have been reported to frequently develop CNS leukemia. The inversion of chromosome 16 or a band 16q22 abnormality is reported to be suggestive of a relatively good patient prognosis.