1) Chronic lymphadenopathy (>6 months) without malignancy, non-infectious or splenomegaly or both

2) Elevation of DN cells, CD3 + TCRαβ + CD4-CD8- (≥1.5% of total lymphocytes or 2.5% of CD3+ lymphocytes) in the context of normal or elevated lymphocyte count



1) Lymphocyte defective apoptosis (in 2 different trials)

2) Somatic or germline mutation in FAS, FASLG, or CASP10


1) Elevation of sFASL plasma levels (>200 pg/mL) or elevated Interleukin-10 plasma levels (>20 pg/mL) or elevated B12 vitamin serum levels (>1500 ng/L) or elevated interleukin-18 plasma levels (>500 pg/mL)

2) Typical immunohistological findings in a review by an expert hematopathologist

3) Autoimmune cytopenias (hemolytic anemia, thrombocytopenia or neutropenia) and elevated levels of immunoglobuline G (polyclonal hypergammaglobulinemia)

4) Family history of lymphoproliferation without malignancy, non-infectious with or without autoimmunity

The definitive diagnosis is realized with the presence of the 2 required criteria plus a primary accessory criterion. A probable diagnosis is based on the presence of 2 required criteria and a secondary accessory criterion.