Diagnostic Criterion Finding
Required criteria
Evidence of Lymphoproliferation Inguinal lymphadenopathy without infectious cause requiring lymph node resection
Double negative T cells CD3+ CD4-CD8- T cells elevated to 7%
Primary accessory criteria
Defective lymphocyte apoptosis FAS-mediated apoptosis decreased at 8% (normal range 57-100%)
Pathogenic FAS *FAS mutation identified, although not known to be pathogenic
Secondary accessory criteria
Elevated biomarkers Elevated B12, soluble FAS ligand, IL-2, IL-10, and IL-18
Autoimmune cytopenias Severe anemia (Hemoglobin low of 2.1 g/dL), neutropenia (Absolute neutrophil count low of 80/mcL), thrombocytopenia (Platelet count low of 2 k/mcL)
Immunohistologic findings Lymph node biopsy showed histiocytosis, positive for CD68 and S100