This specimen shows features appropriate to a myelodysplastic syndrome (MDS) in combination with VEXAS syndrome. The abnormal granulation of the eosinophilic granulocytes is striking. In addition, marked vacuolization is visible, mainly in the eosinophils, and to a lesser extent also in the basophils, neutrophils and blasts.

Vacuolization is characteristic of VEXAS syndrome and is caused by an underlying mutation in the UBA1 gene. This genetic defect leads to impaired protein degradation in the ubiquitin-proteasome system, causing intracellular stress and accumulation of undigested materials. This manifests morphologically in the form of cytoplasmic vacuoles.