Diseases of immune dysregulation

**Definition:** A disease caused by determinants arising after birth, during the antenatal period or genetically inherited factors leading to uncontrolled proliferation of activated lymphocytes and macrophages. This disease is characterised by increased proliferation of morphologically benign lymphocytes and macrophages that secrete high amounts of inflammatory cytokines. This disease may present with fever, rash, jaundice, splenomegaly, lymphadenopathy, histiocytosis, haemophagocytosis, or cytopenia.

**Inclusions:** - histiocytosis of mononuclear phagocytes