CXCL13 and angioimmunoblastic T-cell lymphoma: Histopathologic features observed in specific infiltrates (cutaneous involvement by AITL) include high endothelial venules, reactive B cell infiltrates, Epstein-Barr virus (EBV)-positive B cells, and atypical T cells with a T follicular helper cell immunophenotype, including expression of PD-1, CXCL13, CD10, and BCL6.2