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Pediatric Hemostasis and Thrombosis

PB0631 - Cluster of Paediatric Cases with Thrombosis and Thrombocytopenia in a-3-Month-Period Referred to the Investigation of Thrombotic Anti-Pf4 Disorders (Vitt- Like Disorders)- a Single-Centre Experience

Monday, June 24, 2024
13:45 – 14:45 ICT
Room: Exhibition Hall

    Co-Author(s)

  • LM

    Lida Mentesidou

    PaediatricIan
    First Department of Paediatrics, "P. & A. Kyriakou" Children's Hospital, Athens, Greece
    Athens, Attiki, Greece

  • DD

    Dimitra Dimopoulou

    PaediatricIan
    Second Department of Paediatrics, "Aghia Sophia" Children's Hospital, Athens, Greece
    Athens, Attiki, Greece

    • Presenting Author(s)

  • AD

    Athina Dettoraki, MD, MSc, PhD

    Paediatrician
    Haemostasis and Thrombosis Unit, Haemophilia Centre, "Aghia Sophia"Children's Hospital,Athens
    Athens, Attiki, Greece

    • Co-Author(s)

  • PK

    Panagiota Katsouli

    Paediatrician
    First Department of Pediatrics, Medical School, Aghia Sophia Children’s Hospital, National and Kapodistrian University of Athens, Greece
    Athens, Attiki, Greece

  • CK

    Christina Karastathi

    Paediatrician
    Second Department of Paediatrics, "P. & A. Kyriakou" Children's Hospital, Athens, Greece
    Athens, Attiki, Greece

  • AM

    Aikaterini Michalopoulou

    Paediatrician
    Haemophilia Centre/Haemostasis and Thrombosis Unit, “Aghia Sophia” Children’s Hospital, Athens, Greece
    Athens, Attiki, Greece

  • MB

    Maria Berikopoulou

    Paediatrician
    Second Department of Paediatrics, "Aghia Sophia" Children's Hospital, Athens, Greece
    Athens, Attiki, Greece

  • IA

    Ioanna Anastasopoulou

    Biologist
    Hemostasis Department, Laikon General Hospital, Athens, Greece
    Athens, Attiki, Greece

  • FT

    Flora Tzifi

    PaediatricIan
    Second Department of Paediatrics, "P. & A. Kyriakou" Children's Hospital, Athens, Greece
    Athens, Attiki, Greece

  • TB

    Theodora Bachou

    PaediatricIan
    First Department of Paediatrics, "P. & A. Kyriakou" Children's Hospital, Athens, Greece
    Athens, Attiki, Greece

  • AK

    Anastasia Konidari

    PaediatricIan, Head of Second Department of Paediatrics, "P. & A. Kyriakou" Children's Hospital
    Second Department of Paediatrics, "P. & A. Kyriakou" Children's Hospital, Athens, Greece
    Athens, Attiki, Greece

  • AM

    Anna Messaritaki

    PaediatricIan, Head Second Department of Paediatrics, "Aghia Sophia" Children's Hospital,
    Second Department of Paediatrics, "Aghia Sophia" Children's Hospital, Athens, Greece
    Athens, Attiki, Greece

  • VS

    Vana Spoulou

    Professor Paediatric Infectious Diseases
    First Department of Pediatrics, Medical School, Aghia Sophia Children’s Hospital, National and Kapodistrian University of Athens, Greece
    Athens, Attiki, Greece

  • HP

    Helen Pergantou

    Paediatrician, Head ofHaemophilia Centre/Haemostasis and Thrombosis Unit, “Aghia Sophia” Children’s
    Haemophilia Centre/Haemostasis and Thrombosis Unit, “Aghia Sophia” Children’s Hospital, Athens, Greece
    Athens, Attiki, Greece

Background: Antibodies against Platelet Factor 4 (anti PF4) may activate platelets and induce severe prothrombotic disorders with associated thrombocytopenia. Heparin-induced thrombocytopenia (HIT) is the prototypic anti-PF4 disorder. Αdenovirus vector COVID-19 vaccines triggered the adverse effect “vaccine-induced thrombotic thrombocytopenia (VITT)”, a heparin-independent platelet-activating disorder, caused by anti-PF4 IgG. More and more cases with a VITT-like disorder without previous vaccination are identified.

Aims: To present a cluster of children with thrombosis and thrombocytopenia in a short-term period.

Methods: Data were collected from May to July 2023.

Results: During the 3-month period, 4 children (3/4 girls; mean age: 6.2±1.5 years) with thrombosis and thrombocytopenia were reported. Two had positive nasopharyngeal swab samples for human adenovirus and the other two streptococcal infection. All had fever with respiratory/gastrointestinal symptoms followed by severe headache and nausea for the girls and severe pain in the leg for the boy. They all had severe thrombocytopenia (platelets:19.000-50.000/mm3), coagulopathy (hypofibrinogenemia or/and reduced factor VII levels), elevated d-dimer and thrombotic events (cerebral sinus venous thrombosis for the girls and deep vein thrombosis for the boy). They all had a known history SARS-CoV-2 infection. Heterozygosity for FVLeiden was found in 2/4 children and heterozygosity for FII20210A mutations in 1/4. Testing for lupus anticoagulant, anticardiolipin and anti-β-glycoprotein revealed low risk antiphospholipid syndrome in all. All patients were treated with tinzaparin or enoxaparin, after a single or two doses of intravenous immune globulin and 3/4 received platelets transfusion with prednisolone. One had positive HIT-antibodies (without prior exposure to heparin) and treatment was switched to fondaparinux. However, re-testing with different method did not confirm the result. All children were discharged home with no thrombocytopenia or neurological sequelae.

Conclusion(s): We present a cluster of paediatric cases with thrombosis and thrombocytopenia which may indicate a post infectious (adenoviral or streptococcal) VITT-like disorder. The causality of VITT-like antibodies needs to be confirmed.