33 一位25歲的青年人患有乾癬，騎腳踏車跌倒後在右側大腿有一片擦傷，日後在傷口上長出一片乾癬病灶，此現象是乾癬的那一種特色？

Darier sign Auspitz’s sign

Nikolsky sign Koebner phenomenon

D

KOEBNER PHENOMEN, THINK BERNICE SCAR ON HAND

Darier's sign is a change observed after stroking the skin of a person with systemic mastocytosis or urticaria pigmentosa.

In general, the skin becomes swollen, itchy and red. This is a result of compression of mast cells, which are hyperactive in these diseases. These mast cells release inflammatory granules which contain histamine. It is the histamine which is responsible for the response seen after rubbing the skin