title: Acquired inhibitor against factor IX in a child: successful treatment with high-dose immunoglobulin and dexamethasone.
abstract: The occurrence of acquired inhibitor against factor IX:C is infrequent in haemophilia B patients and is very rare in previously healthy subjects, in whom it is often related to underlying diseases. We describe the case of a 2-year-old girl, who was referred to our hospital with haematomas, without previous bleeding history. Prolonged APTT, normal PT and a factor IX:C level below 1% were found. An inhibitor against factor IX:C was detected (5.5 U mL(-1)). Her father and mother showed normal factor IX:C levels. Treatment with high-dose immunoglobulin (400 mg kg(-1) day(-1) for 5 consecutive days by intravenous infusion) and dexamethasone (4 mg three times a day by intravenous injection for 4 consecutive days) normalized factor IX:C levels and overcame the inhibitor. In conclusion, high-dose immunoglobulin and high-dose dexamethasone are a successful and safe immunosuppressive approach for recovery from inhibitor occurrence.
authors.affiliation: Hematology, Dipartimento di Biotecnologie Cellulari ed Ematologia, University 'La Sapienza' Rome, Italy.
authors.forename: M G
authors.initials: MG
authors.lastname: Mazzucconi
authors.forename: M
authors.initials: M
authors.lastname: Peraino
authors.forename: L
authors.initials: L
authors.lastname: Bizzoni
authors.forename: S
authors.initials: S
authors.lastname: Bernasconi
authors.forename: M
authors.initials: M
authors.lastname: Luciani
authors.forename: G D
authors.initials: GD
authors.lastname: Rossi
mesh_terms: D002675:Child, Preschool; D003520:Cyclophosphamide / Q000627:therapeutic use; D003907:Dexamethasone / Q000627:therapeutic use*; D004306:Dose-Response Relationship, Immunologic; D005164:Factor IX / Q000037:antagonists & inhibitors*; D005260:Female; D006406:Hematoma / Q000628:therapy; D006801:Humans; D016756:Immunoglobulins, Intravenous / Q000627:therapeutic use*; D007166:Immunosuppressive Agents / Q000627:therapeutic use*; D010951:Plasma Exchange; D011241:Prednisone / Q000627:therapeutic use; D016896:Treatment Outcome
chemical_list: D016756:Immunoglobulins, Intravenous; D007166:Immunosuppressive Agents; D003907:Dexamethasone; D003520:Cyclophosphamide; D005164:Factor IX; D011241:Prednisone