The patient came to the clinic 16-January-2007 complaining of a bony lump in the right fronto-parieto-temporal region progressing in size. She noticed this several months without pain. She brought with her brain CT-scan with the diagnosis "fibrous dysplasia". Considering her age, unusual localization of the process for dysplasia, which usually invade the base of the skull, and rapid growth rate, intraossal meningioma was suspected and MRI was requested.

MRI with contrast performed, showing typical intraossal meningioma with wide=spread invasion of the dura with carpet covering the three lobes with epicenter 3 cm above the right pterion.

A wide question mark incision was made and the bone flap was created 2 cm away from the pathologic bony structure. The center of the abnormal bone was bleeding profusely, and bleeding was controlled by bone wax.
The bone flap was elevated and sent for thermal deproteinization with temperature 125 for 15 min.
The pathologic dura was removed with the meningioma carpet, which was abutting the anterior edge of the bone defect.
After thermal coagulation of the bone flap, it was more clear, that the pathologic bone was extending anteriorly, for what secondary bone flap was created anteriorly to make sure the radical resection of the tumor.
The suspected dura was also removed and 4 pieces of large size lyodura were necessary to use to close the dural defect.
The boiled bone was remolded by the high-speed drill so as to regain a normal-looking appearance. The hyperostotic bone was marble-like in consistency.
The 2 bone flaps were fixed together by nylon, and glue. The flaps were put back in place and fixed. and routine closure of the wound.

Smooth postoperative recovery.  She was sent to the ward.

Fibrous dysplasia usually start early in life with young males and it invade the base of the skull. The dura under the fibrous dysplasia is normal and has no pathologic components.
Intraossal meningioma has dural involvement, with a carpet, which could be more wide than the hyperostotic part of the bone.
To prevent recurrence, it is mandatory, to remove all the involved dura and take if feasible 1-2 cm away the pathologic margins of invasion, as in this case.
It is unnecessary to use bone cement or metallic mesh, as in this case, the bone was deproteinized with thermal exposure of the bone flap for 15 min in the autoclave with temperature 125 degrees, Celsius.
During the 27 year period more than 20 operations were performed, returning the boiled bone flap to place. An interesting phenomenon, is the disappearance of the bone flap in the usual skull X-rays in the first 6 months, then its reappearance, despite the fact, that the flap is holding normal in place. It could be explained by the gradual wash-out of the calcium and then the gradual filling of the mineral after this period.
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