The term"interface dermatitis (ID)" refers to a specific histological inflammatory pattern that is characterized by the liquefactive degeneration of basal cells and dense inflammatory infiltration around the vessels in superficial dermis, especially in dermal papilla. ID can be seen in many different inflammatory skin disorders including lichen planus, cutaneous lupus erythematosus, herpes simplex virus infection, viral warts and tumors such as lichenoid actinic keratosis and squamous cell carcinoma. Recent studies have shown that the type-Ⅰ interferon is involved in the pathogenesis of cutaneous disorders pathologically characterized by ID. Interferon Ⅰ, in certain conditions, may induce cytotoxic attacks against basal cells and subsequently cause the development of ID.