Grand Rounds

A Queer Case of Thrombocytopenia in a Child


Department of Clinical Hematology, Seth G.S. Medical College, KEM Hospital, Mumbai, India

Address for Correspondence: Dr. Govind Kendre, Department of Clinical Hematology, Seth G.S. Medical College, Parel, Mumbai, India.
Email: govindken143@gmail.com


Keywords: Pseudothrombocytopenia, EDTA, citrate

Clinical Problem :
A 3-years-old male child was hospitalized for right-sided pneumonia. Complete blood count (CBC) showed hemoglobin 13.5 gm/dl, total leucocyte count- 6800 cells/cumm and thrombocytopenia with a platelet count of < 20,000 cells/cumm on two occasions. There was no history of easy bruisability, petechiae, ecchymosis or bleeding from any site. There was no history of bleeding disorders in family members. Physical examination was normal. CBC by an automated counter in the hematology lab showed hemoglobin of 13 gm%, total leucocyte counts of 10,500 cells/cumm and platelet counts of 10,000 cells/cumm. A peripheral smear examination showed multiple aggregates of platelets (Figure 1). All previous CBCs were done using ethylenediaminetetraacetic acid (EDTA) as an anticoagulant. When the CBC was repeated with Sodium Citrate as an anticoagulant, the platelet count was found to be 2,35,000 cells /cumm.

Figure 1. Peripheral blood smear (Giemsa stain) (1000x): showing platelet clumps.

Why did the child have thromobocytopenia on EDTA samples?


Discussion :
Pseudothrombocytopenia occurs in up to 0.1% of all CBCs and is usually caused by EDTA-dependent platelet agglutinating antibody.1,2 Other mechanisms include artifacts of blood collection, monoclonal platelet agglutinin, platelet reactive cold agglutination and platelet satellitism where platelets form Edta dependent rosetting around neutrophils and monocytes.3 Use of an alternate anticoagulant such as citrate or Heparin may be helpful. However, up to 17% of patients with Edta dependent pseudothrombocytopenia also show this phenomenon with citrate.4 This condition is clinically benign and is not associated with any pathological significance.5 Accurate diagnosis of pseudothrombocytopenia is necessary as unrecognized spurious thrombocytopenia causes significant health expenditure and discomfort to the patients. Unnecessary clinical concern leads to inappropriate therapy such as blood transfusions and withholding of surgical procedures.4 Measurement of platelet counts by modern automated analyzers is more accurate and economical, however, platelet clump "flag" on the CBC must prompt a thorough peripheral blood smear examination.5
This case underlines the importance of routine peripheral blood smear examination and appropriate interpretation of platelet histogram.

Acknowledgment
We thank Dr. Chandrakala S (HOD clinical hematology) and Dr. Farah Jijina for their valuable inputs.

References :
  1. Payne BA, Pierre RV. Pseudothrombocytopenia: a laboratory artifact with potentially serious consequences. Mayo Clin Proc. 1984;59:123-125.
  2. Berkman N, Michaeli Y, Or R, Eldor A. EDTA-dependent pseudothrombocytopenia: a clinical study of 18 patients and a review of the literature. Am J Hematol. 1991;36:195-201.
  3. Qureshi, B. EDTA-Dependent pseudothrombocytopenia. LabMed. 1998;29: 471-473.
  4. Nagler M, Keller P, Siegrist D, Alberio L. A case of EDTA-dependent pseudothrombocytopenia: simple recognition of an underdiagnosed and misleading phenomenon. BMC Clin Pathol. 2014;14:19
  5. Tan G, Stalling M, Dennis G, Nunez M, Kahwash SB. Pseudothrombocytopenia due to Platelet Clumping: A Case Report and Brief Review of the Literature. Case Rep Hematol. 2016;2016:3036476.

Correct Answers :  yes 100%
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