Act quickly. I have HES since May 2021. Started with a rash on arms and ankles, swollen ankles and ended up with severe blood clots in my right foot arteries where due to delay in diagnosis I had leg bypass surgery on Dec 2021. I would recommend to be on blood thinners right away if you see issues like pain and tingling sensation on legs. Your symptoms could be different. I live in Bay Area any my Hematologist diagnosed Lymphotic HES based on bone marrow biopsy. I was on steroids last 10 months and now trying Nucala and interferon alpha 2a injections.