Pediatric Spontaneous Heparin-Induced Thrombocytopenia and Thrombosis Resulting in Thrombotic Storm

Background:

The annual incidence of venous thromboembolism in pediatric patients is approximately 6 out of 1000 in the United States. In rare cases, rapid progression of multifocal thrombosis occurs despite therapeutic anticoagulation with heparin or low molecular weight heparin. Heparin-induced thrombocytopenia (HIT) is a pro-thrombotic disorder caused by an IgG-mediated immune response against platelet factor 4 resulting in platelet activation and risk of thrombosis, classically associated with prior exposure to heparin. The literature reports rare cases of adult patients developing HIT and thrombosis (HITT) without prior exposure.

Objective:

Aim to describe a case of spontaneous HITT in a pediatric patient which has never previously been published in the literature.

Design/Method:

Single subject case report developed with literature review.

Results:

2-year-old male with no past medical history who presented with 5 days of frontal headaches and irritability. Neuroimaging, including CT, MRI, and MRV demonstrated extensive sinus venous thrombosis requiring initial anticoagulation with heparin. However, within 48 hours of initiation, the patient developed significant thrombocytopenia concerning for HIT. Lab testing was positive for both heparin-induced antibody and serotonin release assay, despite no prior heparin exposure. The remainder of the hypercoagulability workup was negative. Heparin was discontinued and the patient subsequently showed inadequate response to initial treatment with first-generation1 direct thrombin inhibitor (DTI) (Argatroban). Due to ongoing severe progressive symptomatic thrombocytopenia and thrombosis concerning for HIIT with thrombotic storm, the patient was treated with DTI (Bivalirubin), high dose methylprednisolone, and anti-CD20 therapy (Rituximab). This resulted in an improved clinical, laboratory, and neuroimaging response, and the patient was able to be gradually weaned off steroid therapy, and transitioned to anticoagulation with warfarin, with plans to remain on long-term anticoagulation.

Conclusion:

This is the first reported case in the literature of spontaneous HIIT in a pediatric patient. Spontaneous HITT is the primary explanation due to fulminant thrombosis and positive heparin-induced antibody and serotonin release assay with no prior heparin exposure, thrombocytopenia without immediate improvement upon heparin discontinuation, and blood smear showing normal red blood cell and platelet morphology. Spontaneous HIIT is a rare but important differential to consider in patients presenting with thrombosis and thrombocytopenia as the treatment differs from that of classic HIT, requiring heparin discontinuation, alternative anticoagulation, and immunomodulation.

No relevant conflicts of interest to declare.