Lymphocytic Vasculitis Involving the Central Nervous System Occurs in Patients With X-Linked Lymphoproliferative Disease in the Absence of Epstein-Barr Virus Infection

X-linked lymphoproliferative disease (XLP) is an immunodeficiency caused by defects in the adaptor molecule SAP. The manifestations of XLP generally Occur following Epstein-Barr virus (EBV) infection and include fulminant mononucleosis, hypogamma-globulinemia and lymphoma. in this report, we describe two unrelated patients with fatal T-cell-mediated central nervous system vasculitis for whom repeated serologic and molecular testing for EBV was negative. In both patients, clonal T-cell populations were observed, but neither demonstrated evidence of lymphoma. Thus, loss of SAP function can lead to dysregulated immune responses characterized by the uncontrolled expansion and activation of T cells independent of EBV infection. Pediatr Blood Cancer 2009;53:1120-1123. (C) 2009 Wiley-Liss, Inc.