Haemophilic pseudotumour of the mandible in a 5-year-old patient.

A haemophilic pseudotumour was identified in the mandible of a 5-year-old male with severe haemophilia A. The patient initially experienced painless swelling of the mandible. Computed tomography revealed a marked enlargement of the lower right mandibular border, which was associated with a low-density area, and irregular absorption of the lingual cortex bone. A malignant tumour was suspected, and a biopsy was performed after the administration of coagulation factor (Factor VII). A histopathologic diagnosis of haemophilic pseudotumour was made and the patient subsequently underwent surgical treatment. A cavity was created in the multilocular bone cyst and surgical curettage and irrigation were performed with the same haemorrhagic control as in the biopsy procedure. The multilocular cyst was contained within a haematoma and was surrounded by thin granular tissue. Three years after surgery, no abnormal signs have been detected by radiography during follow-up examinations. This case involved a rare haemophilic pseudotumour located in the mandible; the pathogenetic mechanism was attributed to pressure necrosis due to intraosseous bleeding.