Burst-forming unit-erythroid assays to distinguish cellular bone marrow failure disorders

Patients with cytopenias and a cellular bone marrow can be a diagnostic and therapeutic challenge. Previous reports suggested a role for progenitor assays for diagnosis and predicting response to therapy. We report the results of Burst-forming unit-erythroid (BFU-E) assays in 48 consultative cases of single or multilineage cytopenias with cellular marrows. The final diagnoses included 17 patients with myelodysplastic syndrome, 9 patients with pure red cell aplasia (non-large granular lymphocytosis [LGL] in etiology], 15 patients with LGL (eight of whom had a single-lineage cytopenia only, whereas the other seven had multilineage cytopenias), and 7 patients with cytopenias associated with systemic inflammation from autoimmune conditions. In this cohort, nonmalignant diseases were well-distinguished from myelodysplastic syndrome by BFU-E growth. Our data suggest that low BFU-E growth (less than 10 BFU-E per 10⁵ marrow mononuclear cells) helps to exclude LGL, pure red cell aplasia, or cytopenias associated with systemic inflammation as a cause of pancytopenia with a sensitivity of 96.8%, specificity of 76.5%, and a predictive value of 88.2% (p = 0.0001). BFU-E growth also was examined to predict treatment response. Of the 29 patients in this cohort treated with immunosuppressive therapy, there was an 86% response rate with 25 responders (11 partial responses and 14 complete responses) and 4 nonresponders. This result correlated with higher BFU-E growth. Our results suggest that BFU-E assays are a useful adjunct in the diagnosis and management of cytopenias in the setting of a normocellular or hypercellular marrows.