A 42-year-old woman was admitted to the hospital for an 11-month history of pustular lesions of the mouth and lips as well as a 5-month history of pustules,ulcer,proliferative plaques on the head,neck and trunk.She had suffered from 8 years of ulcerative colitis.Dermatological examination revealed mild erosion of eyelids,swelling of buccal mucosa and oral lips,as well as typical snail track lesions formed by pustules,exudates and mucilage.There was a large pitchy proliferative plaque sized 20 cm × 10 cm with an elevated margin in the neck as well as palm-to persian walnut-sized proliferative plaques in the prothorax,armpit,periumbilical area and left inguinal area.Histopathology revealed epitheliomatous hyperplasia of the epidermis with the formation of eosinophilic microabscesses,and superficial dermal infiltrate with numerous neutrophils and eosinophils.Direct immunofluorescence tests for IgA,IgG,and C3 were negative.A diagnosis of pyodermatitis-pyostomatitis vegetans was made.The patient was given intravenous methylprednisolone 40 mg/day and symptomatic treatment,which leaded to a gradual subsidence of skin lesions.