患者男,46岁。主诉:左上臂红色斑块20年。现病史:患者20年前左上臂出现黄豆大红色丘疹,逐渐增大成斑块,病程中患者无明显不适。自行使用糖皮质激素类药膏(具体不详),效果不明显,于2015年5月来我科就诊。既往史:既往身体健康。家族史:家族中无家族遗传病史,无类似疾病患者。皮肤科检查:左上臂伸侧一直径约2 cm红色斑块,界限清楚,表面粗糙呈颗粒状,可见色素沉着(图1),未见 Male patient, 46 years old. Chief complaint: left upper left red plaque 20 years. Current medical history: 20 years ago, the patient appeared in the left upper arm big red papules, gradually increased into plaques, the patient’s course of no obvious discomfort. Self-use of glucocorticoid ointment (specific unknown), the effect is not obvious, in May 2015 to our department. Past history: the past, good health. Family history: Family history without family history, no similar diseases. Dermatology examination: left upper arm extensor a diameter of about 2 cm red plaque, clear boundaries, the surface was rough, visible pigmentation (Figure 1), no