title: Cranial hemophilic pseudotumor associated with factor IX deficiency: case report.
abstract: BACKGROUND
  Hemophilic pseudotumor is an unusual complication occurring in only 1% to 2% of patients with severe factor VIII or IX deficiency, and manifests as a progressive enlargement of hematoma by recurrent hemorrhage, often resulting in bone destruction or resorption due to the chronic pressure of osseous hemorrhage. Cranial hemophilic pseudotumors are extremely rare, with only 4 previous cases associated with mild or moderate factor XIII deficiency.
  
  
  METHODS
  A 24-year-old man with moderate deficiency of factor IX developed a cranial pseudotumor as a swelling in the frontal scalp. Blood coagulation profile revealed extended activated partial thromboplastin time (58.2 seconds). Factor IX analysis showed 3% of normal activity. Computed tomography and magnetic resonance imaging demonstrated an extra-axial lesion with bone destruction, enhanced rim, and signal changes consistent with chronic hemorrhage. Surgical removal was performed. Histologic examination disclosed old blood coagulum.
  
  
  CONCLUSIONS
  This case of cranial hemophilic pseudotumor in a patient with moderate factor IX deficiency suggests that cranial pseudotumor should be considered in the differential diagnosis of cranial lesion in a patient with hemophilia, and adequate replacement therapy in the perioperative period is essential to achieve safe surgical removal.
authors.affiliation: Department of Neurosurgery, Aomori Prefectural Central Hospital, Aomori 030-8553, Japan. tomoo49@nsg.med.tohoku.ac.jp
authors.forename: Tomoo
authors.initials: T
authors.lastname: Inoue
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Suzuki
authors.forename: Shinjitsu
authors.initials: S
authors.lastname: Nishimura
authors.forename: Kensuke
authors.initials: K
authors.lastname: Murakami
authors.forename: Michiharu
authors.initials: M
authors.lastname: Nishijima
mesh_terms: D000328:Adult; D001847:Bone Diseases / Q000175:diagnosis / Q000209:etiology* / Q000601:surgery; D005624:Frontal Bone; D006406:Hematoma / Q000175:diagnosis / Q000209:etiology* / Q000601:surgery; D002836:Hemophilia B / Q000150:complications*; D006801:Humans; D008297:Male