Angioimmunoblastic T-cell lymphoma (AITL, sometimes misspelled AILT, formerly known as "angioimmunoblastic lymphadenopathy with dysproteinemia": 747 ) is a mature T-cell lymphoma of blood or lymph vessel immunoblasts characterized by a polymorphous lymph node infiltrate showing a marked increase in follicular dendritic cells (FDCs) and high endothelial venules (HEVs) and systemic involvement..