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.
CASE DESCRIPTION: 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.