CD40LG and reactive arthritis: Exclusion criteria in the differential diagnosis of juvenile arthritis subtypes encompasses: the presence of the IgM-type rheumatoid factor in at least two determinations over a 3-month interval; psoriasis or a history of psoriasis in the patient or a family history; arthritis manifested in a male patient with a positive HLA-B27; symptoms of ankylosing spondylitis, arthritis-related enthesitis, sacroiliitis with inflammatory colopathy, reactive arthritis (Fiessinger-Leroy-Reiter syndrome) with acute anterior iridocyclitis or a positive, if not family or personal history [53,54].