[Case of a horn-shaped osteoma].

A Case of osteoma with horn shape is rare. A 79-years-old man, in whom the osteoma with horn shape was not demonstrated three years ago. Slowly, the osteoma becomes accompanied with pain, and the slow growth of a horn. Computed tomography showed a bone tumor arising from the right parietal bone, but, the patient didn't request treatment. The osteoma changed its form, and an ulcer developed. The patient eventually accepted our advice about surgery, but with bad grace. On operation, the tumor proved to be hard. The tumor was detaches from the skull and the surrounding cranial bone was removed. The histological diagnosis was that it was a case of a compact type osteoma. The postoperative recovery of the patient was satisfactory and his pain disappeared, but, he died of pneumonia on the 40th postoperative day. We believe that the osteoma in our case must have grown slowly with time and ossification of the surrounding tissue.