Eosinophilic granulomatosis with polyangiitis (EGPA), formerly known as Churg-Strauss syndrome, is a rare autoimmune condition characterized by inflammation of small and medium-sized blood vessels, leading to damage in various organ systems. It is associated with an overproduction of eosinophils, a type of white blood cell, and can affect the lungs, skin, heart, gastrointestinal tract, and nervous system.