Polyarteritis nodosa is a rare autoimmune disease that involves inflammation of the blood vessels, specifically medium-sized arteries. This inflammation can lead to damage of the blood vessels and surrounding tissues, causing symptoms such as skin rashes, muscle and joint pain, fever, nerve damage, abdominal pain, and potentially life-threatening complications such as organ damage and aneurysms. Treatment typically involves immunosuppressive medications to control the inflammation and prevent further damage to the blood vessels. Early diagnosis and treatment are crucial to effectively manage the disease and prevent serious complications.