An inguinal LN biopsy appeared as a tumor-cell-rich AITL, with abundant lymphoma cells, clear cytoplasm, and arborizing vessels, and expressed a TFH immunophenotype (CD3+, CD5+, CD7-, CD4+, strong ICOS, and PD1), though CD25 and FOXP3 were also positive. Here, ICOS is linked to neoplasm.