Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Eosinophilic fasciitis ?
    ### Response:
    Eosinophilic fasciitis is a very rare condition in which muscle tissue underneath the skin, called fascia, becomes swollen and thick. Rapid swelling can occur in the hands, arms, legs, and feet. People with this condition have a buildup of eosinophils, a type of white blood cell, in the affected fascia and muscles.
    