Characteristic vacuolisation of granulocytic and erythroid precursors associated with VEXAS syndrome
Jean‐Baptiste Rieu, Ali El Kassir, Laëtitia Largeaud, Jérémie Dion, Thibault Comont, Véronique Mansat‐De Mas
Abstract
A 78-year-old man with Sweet’s syndrome was referred for progressive anaemia. The full blood count showed macrocytic non-regenerative anaemia (haemoglobin concentration 82 g/l, mean cell volume 107 fl, reticulocytes 34 × 109/l) without neutropenia or thrombocytopenia. Bone marrow examination (images, ×100 objective) showed isolated dyserythropoiesis with basophilic stippling (top left), nuclear budding (bottom left), giant erythroblasts with nuclear:cytoplasmic asynchrony (bottom left) and 22% ring sideroblasts (Perls stain, top centre), without blast excess. This result was indicative of a myelodysplastic syndrome with ring sideroblasts and single lineage dysplasia (MDS-RS-SLD). Moreover, large vacuoles were observed in 20% of granulocytic (top right and bottom centre) and 10% of erythroid precursors (bottom right) but not in lymphocytes. Next-generation sequencing (NGS) did not reveal any classical MDS mutations but identified a UBA1 (ubiquitin-activating enzyme 1) M41L mutation (variant allele frequency 71%).