Clinical severity in Japanese patients with neurofibromatosis 1 based on DNB classification.

Neurofibromatosis 1 (NF1) is a genetic disease characterized by cutaneous, neurological and osseous complications. Although clinical manifestations of NF1 are variable, there has been no report on evaluation of severity in patients with NF1. To elucidate the grade of severity of NF1, a retrospective study was conducted in 124 NF1 patients at the Department of Dermatology of Tottori University Hospital in 2007-2016. The DNB classification (dermatological, neurological and bone manifestations) in Japan was used for assessment. Based on our current epidemiological data, there were 55 patients (44.3%) in stage 1, 23 (18.6%) in stage 2, three (2.4%) in stage 3, one (0.8%) in stage 4 and 42 (33.9%) in stage 5. The grade of severity in patients with NF1 tended to be higher with aging. Remarkably, 61.8% of the patients in stage 5 had diffuse plexiform neurofibromas with functional disability. We should pay attention to diffuse plexiform neurofibromas that greatly affect quality of life in patients with NF1.