[Japanese cases of hyperostosis frontalis interna].

Although hyperostosis frontalis interna is common in the western countries, it has been rarely reported in the literature in Japan. We had a chance to observe 5 cases diagnosed as hyperostosis frontalis interna. They were found among 10,902 patients who came to our hospital from August 1, 1993 to September 30, 1995. All the patients in these five cases are females aged 67 to 85 (mean = 74.2 years). Four of the 5 cases had been treated as hypertension, 2 as diabetes mellitus, and 1 as hyperlipoidemia. Two cases were accompanied by unruptured aneurysms. The pathology of one case accompanied by chronic subdural hematoma revealed no apparent development of Haversian systems of bone. It seems that the prevalence of this disease in Japan would increase from now on due to the fact that the life style and the diet among Japanese people has been getting westernized.