Here we report, by lymph node (LN) flowcytometry, that we early recognized ultra early PTLD after an HLA-matched sibling allo-HSCT followed by a successful treatment with anti-CD20 antibody (rituximab) in a patient in progress disease for angioimmunoblastic T-cell lymphoma (AITL). Here, MS4A1 is linked to angioimmunoblastic T-cell lymphoma.