E. F. stands for "Eosinophilic Fasciitis," a rare autoimmune condition characterized by inflammation and thickening of the skin and underlying tissues. It primarily affects the fascia, which is the connective tissue surrounding muscles, nerves, and blood vessels. Symptoms often include swelling, pain, and a change in skin texture, typically starting in the arms and legs. The exact cause of E. F. is not well understood, but it may be associated with certain medications, infections, or other autoimmune diseases. Diagnosis usually involves a combination of clinical evaluation, imaging studies, and sometimes a biopsy of the affected tissue to confirm inflammation and rule out other conditions.