Abstract
BACKGROUND: Cardiac tamponade is a rare but serious manifestation of autoimmune polyglandular syndrome Type 2 (APS 2). Patients often present with symptoms of thyroid dysfunction and adrenal insufficiency, but the insidious onset of the disease may lead to delayed diagnosis, which can progress rapidly to haemodynamic instability requiring urgent intervention. CASE SUMMARY: A 39-year-old previously healthy male was admitted with cardiac tamponade complicated by cardiac arrest requiring emergent pericardiocentesis. An extensive work up revealed primary adrenal insufficiency and Hashimoto's thyroiditis. His positive autoantibodies to thyroid peroxidase and 21-hydroxylase combined with rapid improvement with initiation of corticosteroids and levothyroxine confirmed a diagnosis of APS 2. DISCUSSION: Although this disease is often difficult to diagnose given its vague symptoms, it should be considered in the differential diagnosis for young patients presenting with pericardial effusion or cardiac tamponade of unknown origin. Early diagnosis and management are critical and often result in rapid improvement after appropriate treatment.