Rituximab induction therapy for de novo ANCA associated vasculitis in pregnancy: a case report

BACKGROUND: The diagnosis of antineutrophil cytoplasmic antibody (ANCA) associated vasculitis (AAV) is rare in pregnancy but potentially life threatening. There are no randomized controlled trials to guide the management of AAV in pregnancy and fetal safety data remains limited. Rituximab administration, a treatment for AAV, has been reported in pregnant women with reassuring fetal outcomes in the oncology and rheumatology literature; however, no published reports describe its use in AAV. CASE PRESENTATION: We present a case of de novo myeloperoxidase positive (MPO) AAV diagnosed at 22 weeks gestation. Clinical presentation included elevated serum creatinine at 177 μmol/L, hematuria and nephrotic range proteinuria along with high-titre MPO. Diagnosis was confirmed by renal biopsy. Patient was treated with methylprednisolone IV followed by oral prednisone 70 mg daily and Rituximab 650 mg IV weekly for four weeks followed by azathioprine maintenance therapy and prednisone taper. Delivery occurred at 29 weeks gestation via cesarean section for maternal neurologic symptoms concerning for preeclampsia. Maternal and fetal CD + 19 cells were depleted at time of delivery with associated fetal lymphopenia in the absence of infection or other complications related to Rituximab use. The patient experienced a reduction in proteinuria and inflammatory markers following Rituximab therapy; however, serum creatinine increased to 375 μmol/L by 11 weeks post-partum. CONCLUSION: We report the first use, to our knowledge, of Rituximab with corticosteroids for induction therapy of AAV in pregnancy.