Suspected ALPS with clinical and laboratory findings: Three patients-three different diagnoses

Autoimmune lymphoproliferative syndrome is a rare genetic disorder characterized by dysregulation of the immune system due to defective Fas mediated lymphocyte apoptosis. The clinical spectrum includes lymphoproliferative disease with lymphadenopathy, hepatomegaly, splenomegaly and an increased risk of lymphoma, as well as autoimmune disease typically involving blood cells. Definitive diagnosis is made by demonstrating infectious/non-malignant chronic lymphoproliferation for more than six months, high CD3+CD4-CD8- T Cell and defective lymphocyte apoptosis or one of the FAS, FASL, CASP10 mutations. Since clinical and laboratory findings may overlap with other immune dysregulation or autoimmune diseases, differential diagnosis of autoimmune lymphoproliferative syndrome remains essential. Here, we present three cases of suspected autoimmune lymphoproliferative syndrome with clinical and laboratory findings, which resulted in three different diagnoses (chronic idiopathic thrombocytopenic purpura, ALPS-like and ALPS) after diagnostic evaluations. For all three cases, next-generation sequencing, flow cytometric analysis, protein expression and Fas mediated lymphocyte apoptosis with functional assays were performed.