New-Onset ANCA-Associated Vasculitis in Pregnancy Successfully Treated With Rituximab: A Case Report and Literature Review.

Development of new-onset antineutrophil cytoplasmic antibody-associated vasculitis (AAV) in pregnant women is extremely rare. Thus, treatment options are not well established. We report the case of a woman diagnosed with rapidly progressive glomerulonephritis due to new-onset anti-myeloperoxidase AAV during the 11th week of pregnancy and discuss the case in the context of available literature. Rituximab and low-dose corticosteroids were used as an induction treatment, and the patient stayed in remission throughout the rest of pregnancy without any detectable side effects to the patient or the newborn. As rituximab placental transfer increases during the third trimester and may induce B-cell depletion in the newborn, a small dose of azathioprine was used as a maintenance treatment at the end of pregnancy when partial B-cell repletion appeared. To our knowledge, this case reports the first documented successful treatment of AAV with rituximab in pregnancy without any side effects and represents the fourth reported case of rituximab administration for de novo AAV in a pregnant woman. The administration of rituximab early during the pregnancy with subsequent azathioprine administration in the third trimester combines the high effectivity of rituximab induction treatment with azathioprine that does not comprise the risk of B-cell depletion and subsequent several months-long sustained rituximab-induced immunosuppression in the newborn.