Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Cheilitis glandularis ?
    ### Response:
    Cheilitis glandularis is a rare inflammatory disorder of the lip. It is mainly characterized by swelling of the lip with hyperplasia of the salivary glands; secretion of a clear, thick mucus; and variable inflammation. Enlargement and chronic exposure of the mucous membrane on the lower lip becomes affected by the environment, leading to erosion, ulceration, crusting, and, occasionally, infection.
    