PB0241 - Acquired Inhibitors: Two Case Studies in Pediatrics

Background: Acquired inhibitors are rare in pediatrics and management is complex due to limited literature. Acquired inhibitors are due to post-infectious, autoimmune, malignant, drug or idiopathic conditions and treatment options include prednisone, cyclophosphamide, rituximab and IVIG.

Aims: Report management of two cases of acquired inhibitors in pediatric patients

Methods: Literature review

Results: Case 1: A previously healthy 4-year-old boy presented with ecchymoses and mobility restricting edema of left extremities without hemarthrosis. His lab workup showed: hemoglobin 5.4g/dl, PTT 114s, and Factor VIII < 1% with a high titer inhibitor (35.2 Bethesda units). A secondary cause was not found. He received supportive treatment with FVIII and recombinant FVIIa. He was treated with prednisone 1mg/kg/day with normalization of his PTT and FVIII level. Our patient is now 5 months in remission off steroids.

Case 2: A 12-year-old female previously diagnosed with refractory chronic ITP with an inconclusive autoimmune workup presented with a left psoas hematoma. Her Hgb was 7.5g/dl, platelet 92K/ul, PT 39s, INR 3.4, PTT 142s and mixing studies demonstrated an inhibitor. Additional workup was significant for a factor II level of 9%, elevated lupus anticoagulant and positive ANA and dsDNA. She was treated with FFP, recombinant FVIIa and Vitamin K for acute bleeding then started on prednisone 2mg/kg/day for lupus anticoagulant hypoprothrombinemia syndrome. As an outpatient, she was started on hydroxychloroquine. She is currently on a prednisone wean, now at 30mg daily with stable PTT and normal factor II. She has improving strength and sensation of her left hip and extremity and decreasing size of the hematoma 2 months after her initial presentation.

Conclusion(s): Diagnosis and management of acquired inhibitors in children is challenging due to their rarity. Management includes treating and preventing hemorrhagic complications using high dose steroids. These cases demonstrate the complexity of diagnosis and management of acquired inhibitors in the pediatric population.