A case of neurofibromatosis-1 in which severe bleeding was observed from a neurofibroma under the scalp

Neurofibroma is a representative external abnormality observed along with café-au-lait spots in association with neurofibromatosis type 1 (NF-1). We encountered a case of NF-1 in which severe bleeding was observed from a neurofibroma under the scalp due to minor trauma. Only four similar cases have been reported in the past literature and we believed that it was a significantly rare case, and we herein report the case with bibliographical considerations. The subject was a 23-year-old male. He was gently hit on the right side of the head during work and the bruised site gradually became bloated. Even on the following day, the bloating continued and he also started feeling severe pain, and as a result, he visited our emergency department. A head CT scan revealed a subcutaneous high-density area from the right-frontal area of the head to the side of the head that appeared to be a hematoma. The pain was severe and we therefore performed emergency surgery to remove the subcutaneous hematoma, but due to severe bleeding during the operation, we ultimately removed only part of the hematoma. However, because the pain was relieved, he was discharged from the hospital and he subsequently stopped visiting the hospital regularly. Three years later, he visited our department again with similar head bloating due to a mild head bruise. When surgery was performed again, an obvious neoplastic lesion was observed along with the subcutaneous hematoma. The pathological findings suggested it was a neurofibroma but no malignant findings were observed.