MDS in patients with VEXAS. MDS in patients with VEXAS is associated with hypercellular BM (panel A: H&E stain; original magnification ×500) with dysplastic megakaryocytes, including micromegakaryocytes highlighted by CD61 immunohistochemistry (IHC) on the core biopsy (panel B: original magnification ×500). Dysmegakaryopoiesis can be seen on aspirate smears, including (C) micromegakaryocytes, (D) megakaryocytes with vacuoles, and (E) megakaryocytes with separated nuclear lobes. Dyserythropoiesis including (F-G) binucleation and multinucleation, megaloblastic changes, and nuclear budding are common. Dysmyelopoiesis can be striking with abnormal maturation including (G) binucleation and maturation asynchrony, (H) binucleated eosinophilic myelocytes, (I) hypogranular forms, and (J) myeloid cells with abnormal morphology and vacuoles. All aspirate images show Wright-Giemsa–stained smears; original magnification ×1000.