Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Pityriasis lichenoides chronica ?
    ### Response:
    Pityriasis lichenoides chronica is the mild, chronic form of pityriasis lichenoides, a skin disorder of unknown cause. This condition is characterized by the gradual development of symptomless, small, scaling papules that spontaneously flatten and regress over a period of weeks or months.
    