Abstract
A case of diploic epidermoid cyst in the left parietal bone is reported. A 33-year-old woman visited our hospital with a history of headache. A skull x-ray showed an osteolytic focal lesion in the left parietal bone. Computed tomography (CT) revealed a well-demarcated hypodense diploic mass and the bony destruction of both inner and outer tables. Magnetic resonance imaging (MRI) also revealed a mass with low signal intensity on the Tl weighted image and high signal intensity on the T2 weighted image, respectively. MRI with a Gadolinium-based contrast medium showed negative enhancement, essentially in the tumor, and dura mater attached directly to the tumor. To know the details of the shape and the size of the craniectomy in advance, a three-dimensional plaster-cast model of the skull that had the same form as the host bone was made before surgery using a computer-aided design in accordance with the patient's three-dimensional CT image data. At surgery, the tumor didn't show any adherence to the dura mater or even to periostper se. The diploic tumor was totally extirpated including the adjacent bone of the skull, and additionally a cranioplasty using hydroxyapatite ceramic was performed concurrently. A piece of hydroxyapatite ceramic was successfully implanted in the site of the bone defect and some trimming was performed using a device for drilling bone. In the report, we confirmed that a preoperatively designed ceramic model is crucial in the performance of cranioplastic surgery, particularly in the treatment of a cranial bone defect using hydroxyapatite ceramic.
