A red, blue, or brown spot on the skin can refer to a temporary brown pigmentation that occurs after subcutaneous bleeding or eczema has healed, but it usually refers to a congenital skin malformation called a nevus, a type of mole. Most nevus do not disappear naturally. Not all nevus are present at birth, and many become noticeable at a certain age. When various types of nevus are combined, such as in Recklinghausen's disease or Pringle's disease, or when they are accompanied by visceral lesions, they are called phacomatosis, and are dominant hereditary disorders, but ordinary birthmarks are not hereditary. Source: Heibonsha World Encyclopedia, 2nd Edition Information |
皮膚にみられる赤,青,褐色などの斑で,皮下出血や湿疹が治ったあとの褐色の色素沈着など一時的なものをさすこともあるが,普通には先天的な皮膚の奇形である母斑nevusをさし,ほくろもこの一種である。母斑の多くは自然に消えることはない。また,すべてが生下時から認められるわけでもなく,ある年齢から目立ってくるものも多い。レックリングハウゼン病やプリングル病などのように種々の母斑が組み合わさってみられたり,内臓病変をともなうものは母斑症phacomatosisと呼ばれ,優性の遺伝性疾患であるが,普通のあざは遺伝することはない。
出典 株式会社平凡社世界大百科事典 第2版について 情報 |
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