Séronégativité et anti-CD20 : lorsqu’un traitement compromet le diagnostic

As anti-CD20 treatments are increasingly used in our internal medicine practices, it is important to keep a critical eye on the results of negative serologies in these situations. Direct tests (PCR, cultures, NGS, etc.) should therefore be preferred for diagnosing infections in patients on anti-CD20 therapy in case of a negative indirect test (serology). Furthermore, the absence of seroconversion seems to favor a more severe clinical picture in case of Lyme borreliosis (neurological symptoms), associated with rather rare manifestations (hepatitis, multiple erythema migrans).