03 January 2026
: Case report 
A Case of VEXAS Syndrome Initially Masked as Myelodysplastic Syndrome: Importance of Marrow Vacuolization and UBA1 Testing: A Case Report
Challenging differential diagnosis, Diagnostic / therapeutic accidents, Unusual setting of medical care, Rare disease, Clinical situation which can not be reproduced for ethical reasons
Ehsan Shahverdi ABCDEF 1, Petra Mundmann ABCDEF 1, Christian Pohlkamp ABCDEF 2, Safae Dirare ABCDEF 1, Islam Hussein Mohamed ABCDEF 1, Hüdanur Semerci ABCDEF 1, Corinna Petz ABCDEF 1*DOI: 10.12659/AJCR.950181
Am J Case Rep 2026; 27:e950181
Table 2 Case timeline (CARE Guidelines format).
| Timepoint | Clinical event | Findings/results | Interpretation |
|---|---|---|---|
| Several months earlier | Initial suspicion of monoclonal gammopathy | Immunofixation, immunoglobulin levels, free light chains normal; C282Y mutation detected; no MYD88 mutation | Monoclonal gammopathy not confirmed; differential diagnosis included medication-associated anemia (hydroxychloroquine) and hereditary hemochromatosis (HFE heterozygous variant, low clinical significance) |
| First bone marrow biopsy | Bone marrow evaluation | Hypercellular marrow, dysplastic changes, 8% ring sideroblasts, small clonal plasma cell population (9%), macrophage activity ↑, mast cell proliferation | Suggestive of myelodysplastic syndrome (MDS)-like process; plasma cell myeloma could not be excluded; toxic dysplasia possible |
| Immunocytology | Cell surface marker analysis | Aberrant CD11b, CD13; reduced CD71 in erythroid lineage; plasma cells 0.9% with regular expression; mast cells rare and non-aberrant | No definitive evidence of MDS, myeloma, or lymphoma |
| Histology | Histological marrow assessment | Reactive hyperplastic hematopoiesis; plasma cells ~20% | Early-stage myeloma suspected; alternative explanation: medication toxicity |
| External re-evaluation | Second pathology review | Hypocellular marrow, mild plasma cell increase without aberrant phenotype | No evidence of plasma cell myeloma or B-NHL |
| Repeat bone marrow biopsy | Diagnostic re-assessment | Prominent vacuolization in erythroid/myeloid precursors; UBA1 mutation (c.122T>C, p.Met41Thr); MDS-like changes | Diagnosis: VEXAS syndrome with concomitant MDS |
| Treatment | Therapeutic decision | Azacitidine initiated | Chosen due to overlap with MDS and evidence of efficacy in VEXAS |