[A case of cranial osteomyelitis after head injury with exaggeration and remission for thirty years].

We report a case of cranial osteomyelitis after head injury with exaggeration and remission for 30 years. A 41-year-old man was referred to our hospital with redness, swelling and pain in the left frontal region. He had noted a hard mass in the same region after an injury at the age of 12 years, and local heat and redness again in the same region which had disappeared without definite treatment at the age of 20 years. Presently, skull roentogenogram showed an erosive lesion in the left frontal bone. Plain CT revealed bone defect, epidural mass lesion, calcification of the dura mater and thickness of the extracranial soft tissue in the left frontal region. T1-weighted MR images showed an isointense lesion and T2-weighted MR images showed a high intensity lesion in the inner table and a diploic layer in the left frontal bone. 99thTc MDP bone scinntigram showed abnormal uptake in the same region. Operation performed through a left frontotemporal craniotomy revealed a degeneration of temporal muscle and frontal bone, and granulation tissue and pus in the subcutaneous and epidural spaces. These were removed together with the calcified dura mater. The subdural space was intact. Dural plasty was performed using fascia lata, but the craniotomied bone was replaced. Histological examination revealed typical findings of osteomyelitis. Postoperative course was uneventful, and he was discharged without neurological deficit. Cranioplasty was performed 8 months after the first surgery. The mechanism by which osteomyelitis continued over a long course of time was suspected to be the formation of a focus of recurrent inflammation due to the head injury 30 years earlier.