Does Bicytopenia Include Leukopenia?
Yes, bicytopenia can include leukopenia—it refers to the reduction of any two of the three blood cell lines (erythrocytes, leukocytes, or platelets), so leukopenia combined with either anemia or thrombocytopenia qualifies as bicytopenia. 1
Definition and Classification
Bicytopenia is defined as the reduction of any two cell lines among red blood cells, white blood cells, or platelets. 1 The three possible combinations are:
- Anemia with thrombocytopenia (most common, 61% of cases) 1
- Anemia with leukopenia (second most common, 26% of cases) 1
- Leukopenia with thrombocytopenia (13% of cases) 1
Therefore, leukopenia is explicitly included in two of the three bicytopenia patterns.
Clinical Context in Myelodysplastic Syndromes
The WHO classification of myelodysplastic syndromes specifically addresses bicytopenia in diagnostic criteria. In refractory cytopenia with unilineage dysplasia (RCUD), bicytopenia may occasionally be observed in peripheral blood even when only one myeloid lineage shows dysplasia in the bone marrow. 2 However, when pancytopenia (all three cell lines reduced) is present with unilineage dysplasia, these cases should be classified as MDS-unclassified (MDS-U) rather than RCUD. 2
Diagnostic Significance
Bicytopenia serves as an important haematological indicator that typically implies insufficient production in the bone marrow, distinguishing it from isolated single cytopenias. 3 The presence of bi- or pancytopenia warrants more extensive evaluation including:
- Peripheral blood smear examination to assess for dysplasia and determine which white blood cell lines are affected 4, 3
- Consideration of bone marrow examination, particularly in unexplained persistent cases 4
- Evaluation for underlying causes including non-malignant conditions (56%), infectious diseases (31.7%), malignancies (8.3%), and drug-induced etiologies (4%) 1
Common Pitfalls
When evaluating bicytopenia that includes leukopenia, clinicians should recognize that the clinical presentation varies by etiology. Fever and lymphadenopathy are most frequent in infectious causes, while pallor, bleeding, hepatomegaly and splenomegaly predominate in non-malignant conditions. 1 The risk of serious infection increases substantially when leukopenia is severe (neutrophil count <500/mcL), requiring prompt antimicrobial therapy. 4