A 21-year-old male was admitted to the Neurosurgery Department for presenting nodules in the left parietal region that had increased in volume over the last 7 months.
Relevant personal history included: moderate haemophilia A and surgery for scaphocephaly in childhood (craniectomy + silicone bands + bone fixation with haemoclips). She presented spontaneous intraparenchymal cerebral haematoma which was treated conservatively. There were no known episodes of trauma.
Physical examination revealed a painless, non-pulsatile, elastic tumour with a smooth surface, covered with normal scalp and measuring 5x3x3 cm in the left parietal region. The neurological examination was normal.

Laboratory findings were: haemoglobin, 16g/dl; haematocrit, 50%; leucocytes, 6710, with a normal differential count; platelets, 211000; prothrombin activity, 97%; APTT: 59sec. Factor VIII: 19%.
Plain X-ray and CT scan of the skull showed an osteolytic lesion of sclerotic margins at the left parietal level with erosion of the external and internal table and expansion of the diploe. MRI revealed a parietal nodule on the same side, well demarcated, with different signal areas inside, with haemoglobin in different stages of evolution: high signal density for methaemoglobin and low signal density for deoxyhaemoglobin.

CT scan of the chest, abdomen and pelvis, as well as bone scintigraphy, ruled out tumour or bone metastasis. The patient received 50U/kg/d Factor VIII prior to surgery which increased his Factor VIII level to 89% of normal. Throughout the operation he received a continuous intravenous infusion of 5U/kg/h of Factor VIII.

Surgical intervention
Under local anaesthesia, the scalp was incised over the tumour and subperiosteal dissection revealed elevation and erosion of the external table, containing zygatricial fibrous tissue around a haematoma in various stages of organisation and, in addition, plastic tissue (silicone bands). The inner table was thinned, with irregular beading and a bony defect.
The haematoma, granular tissue and foreign body (silicone) as well as the thinned and elevated outer table were removed to normal bone thickness and appearance by bone curettage.
Histological examination confirmed the presence of old haematoma and granulation tissue.
After surgery, Factor VIII remained at 80% of normal activity until the suture material was removed.

