Anti-neutrophil cytoplasmic antibody-associated vasculitis following allogenic bone marrow transplantation and chronic graft-versus-host disease: a rare case.

Anti-neutrophil cytoplasmic antibody-associated vasculitides (AAV) are rare autoimmune disorders typically involving the lungs and kidneys. A few case reports have described an association with hematopoietic stem cell transplant (HSCT). We present a case of myeloperoxidase-positive AAV with predominant renal involvement in a 49-year-old male with a history of acute myeloid leukemia treated with allogenic HSCT and complicated by chronic graft-versus-host disease (GVHD). He presented with rapidly progressive glomerulonephritis, and kidney biopsy revealed pauci-immune necrotizing crescentic glomerulonephritis. Treatment with methylprednisolone pulses followed by oral prednisolone, rituximab, and plasmapheresis led to improved kidney function and a tailored rituximab maintenance regimen was followed. However, a renal-limited relapse occurred at 15 months, requiring repeat induction therapy. Dialysis was avoided, but renal function only partially recovered. This case suggests that AAV can develop after HSCT and GVHD and highlights the importance of long-term follow-up and further research into underlying mechanisms.