Epidemiology and clinical characteristics of bullous congenital ichthyosiform erythroderma (keratinolytic ichthyosis) in Japan: Results from a nationwide survey

Background: Detailed nationwide surveys of the epidemiologic and clinical characteristics of bullous congenital ichthyosiform erythroderma (BCIE) (novel synonym: keratinolytic ichthyosis) in a large population have not been performed previously to our knowledge. Objective: We sought to estimate the number of patients with BCIE who visited dermatology departments in Japan in 2002 and to clarify the clinical and epidemiologic features of the disease. Methods: A nationwide mail survey was sent to dermatology departments and consisted of an initial survey to estimate the number of individuals with BCIE and a second survey to obtain data on the clinical characteristics of these patients. Results: The total number of patients with BCIE in Japan was estimated to be 55 (95% confidence interval, 35-75). Clinical data were able to be collected from 28 cases. Clinical manifestations included rash in 27 cases (96.4%), erythroderma in 19 cases (67.9%), and generalized blistering in 15 cases (57.7%). Approximately 75% of patients younger than 20 years showed generalized blistering. Hystrixlike scales were present in 8 female patients (57.1%), whereas large scales were present in 8 male patients (57.1%). Among the 19 patients for whom histopathological information was available, 17 (89.5%) showed granular degeneration. Limitations: Patients with BCIE who have few subjective symptoms may not have visited a dermatology department, potentially resulting in an underestimation of the number of patients with BCIE. Conclusion: Important epidemiologic and clinical information on characteristics of BCIE in Japan was obtained, including an estimate of the total number of patients with BCIE in Japan.