Below is an instruction from Human. Write a response.
    ### Instruction:
    What causes Pityriasis lichenoides et varioliformis acuta ?
    ### Response:
    What causes pityriasis lichenoides et varioliformis acuta? The exact underlying cause of pityriasis lichenoides et varioliformis acuta (PLEVA) is unknown. Some scientists suspect that it may occur due to an exaggerated immune response or hypersensitivity to an infection.
    