SF3B1-mutated MDS coexisting with β-thalassemia trait

Rationale: β-Thalassemia trait and myelodysplastic syndrome (MDS) may occur in the same patient. In patients with MDS and microcytosis, an important diagnostic consideration is whether the thalassemic phenotype represents a preexisting hereditary disorder or an acquired abnormality related to the myeloid clone. We report on a patient with SF3B1-mutated MDS and β-thalassemia trait, supported by longitudinal hematologic and molecular findings, and discuss the diagnostic distinction between these conditions. Patient concerns: An 81-year-old male presented with fatigue and fever, and laboratory investigations revealed microcytic anemia. Further evaluation identified SF3B1-mutated MDS with concomitant β-thalassemia trait. Diagnoses: The patient was diagnosed with SF3B1-mutated MDS with concomitant β-thalassemia trait based on bone marrow morphology and molecular studies. Interventions and outcomes: Following conservative management, the patient was discharged. During the available follow-up period, the patient remained clinically stable across three outpatient visits for complete blood count monitoring. Lessons: This case illustrates the importance of distinguishing hereditary β-thalassemia from acquired thalassemic phenotypes in patients with MDS and microcytosis. Longitudinal hematologic history, hemoglobin analysis, and molecular testing can help determine whether microcytosis predates the clonal myeloid disorder. The available case-based literature does not permit a reliable estimate of the prevalence of this co-occurrence or comparison with a control population.