Confine congests all round bubble, aching feeling is not had when squashing with the hand, several in the future nodal and epithelial exfoliate, top forms small ulcer, general but self-healing.

• 泡周围局限充血，用手挤压时无疼痛感，数日后结节上皮剥脱，顶端形成小溃疡，一般可自愈。