38.3 Primary Immunodeficiencies: When is it not just "JIA"

Juvenile Idiopathic Arthritis (JIA) is sometimes considered a diagnosis of exclusion as the name signifies that no cause is evident for this form of arthritis. Despite this JIA has some classical clinical features and many categories are defined based on the phenotype. Since there is no diagnostic test for JIA, diseases that can mimic JIA, including Primary Immunodeficiencies (PID) can sometimes be misdiagnosed as JIA. The clues to suspecting PIDs are early age of onset, presence of family history, increased susceptibility to infections, unusual features like urticaria, interstitial lung disease, sensorineural hearing loss and poor response to conventional therapy, amongst others. This review will highlight the basics of PIDs and will discuss PIDs that can present with arthritis and hence can be confused with JIA.