Pseudoneutropenia from cold agglutinin leucoagglutination

Pseudoneutropenia or low leucocyte count secondary to leucoagglutination is caused by ethylene diamine tetra acetic acid (EDTA) or cold agglutinins and is seen in benign and malignant disorders. We report a 34-year-old lady who was admitted with fever, vomiting, respiratory distress and productive cough. Complete blood count (CBC) at initial presentation revealed low haemoglobin (11.6 g/dL), total leucocyte count (TLC) (5900/mm3) with 50% polymorphs. Peripheral blood smear showed leucocytes in clusters. Another sample was asked for in citrate anticoagulant which showed a TLC of 5900/mm3 with 50% polymorphs and evidence of auto agglutination. Another collected in a prewarmed ethylene diamine tetra acetic acid (EDTA) tube, CBC showed a TLC of 9800/mm3 with 39% neutrophils suggestive of pseudoneutropenia due to cold agglutinins.