LETTER TO THE EDITOR Candida parapsilosis misleading the automated absolute and differential white blood cell count Silvia Verdesoto-Cozzarelli 1 & Concepción Prats-Martín 1 & Rosario M. Morales-Camacho 1 & Concepción Pérez de Soto 1 & Maite Ruiz 2 & José M. de Blas 1 & Ricardo Bernal 1 & José A. Pérez-Simón 1 Received: 31 August 2016 /Accepted: 2 October 2016 # Springer-Verlag Berlin Heidelberg 2016 Dear Editor, A 13-year-old male with a previous history of T lymphoblastic leukemia was admitted into the hospital with an early relapse after allogeneic stem cell trans- plantation from unrelated donor. Salvage chemotherapy was initiated with FLAG-Ida (fludarabine, cytarabine, idarubicin, and granulocyte colony-stimulating factor). He carried a central venous catheter and parenteral nutrition was initiated at his admission. On the seventh post-chemotherapy day, the patient developed febrile neutropenia and was treated empirically with antibi- otics and then micafungin. The latter was stopped after 17 days of treatment due to liver toxicity, apyrexia and negative infectious screen. At that time, his blood count demonstrated severe pancytopenia (hemoglobin concentration 7.6 mg/dL, neutrophil count 0.1 × 10 9 /L, and platelet count 7 × 10 9 /L). Three days later, the pa- tient developed a sinusitis and was started on liposo- mal amphotericin-B. Forty-eight hours later, using a SYSMEX XN-9000 hematology analyzer, a full blood count showed: white blood cell (WBC) count 3.9 × 10 9 /L (with a differential count of 26 % neutrophils, 55 % lymphocytes, 15 % monocytes, 1 % eosinophils, and 3 % basophils), hemoglobin concentration 9.8 mg/ dL, and platelet count 13 × 10 9 /L. However, the ana- lyzer revealed an abnormal image in the WBC differ- ential channel: a cloud of dots with no separation of the different cell populations (Fig. 1a) compared to the normal image (Fig. 1b). For this reason, a blood film was made. Morphological examination showed abso- lute neutropenia, very isolated monocytes, all of which had phagocytized budding yeasts (Fig. 1c, d ) and many extracellular pseudohyphae and budding yeast forms (Fig. 1e). The patient was therefore maintained on amphotericin-B. Three days later, Candida parapsilosis was identified from peripheral blood cul- ture; however, a careful search of the blood film no longer disclosed any yeast forms at that time. Finally, the patient died within 2 months of admission with active leukemia. Microorganisms in a peripheral blood film can rarely result in spurious WBC counts [1–5]. Abnormal WBC differential scattergram by automated hematology ana- lyzers should be a red flag and careful examination of a blood film must be carried out. In this case, C. parapsilosis, arranged in clusters or phagocytized by monocytes, led to the spurious automated absolute and differential WBC count. The observation of Candida phagocytosis by white blood cells in a periph- eral blood film is a rare phenomenon [6–9], monocytes instead of neutrophils phagocytizing is exceptional. The correct diagnosis allows to detect the infection and the true absolute neutropenia with important therapeutic implications. Electronic supplementary material The online version of this article (doi:10.1007/s00277-016-2851-3) contains supplementary material, which is available to authorized users. * Rosario M. Morales-Camacho rosafranco_24@yahoo.es 1 UGC de Hematología. Hospital Universitario Virgen del Rocío, Instituto de Biomedicina de Sevilla (IBIS)/CSIC/Universidad de Sevilla, Seville, Spain 2 UGC de Enfermedades Infecciosas, Microbiología and Medicina Preventiva. Hospital Universitario Virgen del Rocío, Instituto de Biomedicina de Sevilla (IBIS)/CSIC/Universidad de Sevilla, Seville, Spain Ann Hematol DOI 10.1007/s00277-016-2851-3