Successful induction of granulomatosis with polyangiitis with tacrolimus.

We report a 50‑year‑old female who presented with inflammatory arthritis, upper respiratory tract symptoms, and microscopic hematuria with nephrotic range proteinuria. Antineutrophil cytoplasmic antibodies (ANCA) were detectable and kidney biopsy showed pauci‑immune focal necrotizing crescentic glomerulonephritis. She was treated with pulse intravenous cyclophosphamide (CYC) and prednisolone. Patient developed severe leucopenia after the first dose and subsequently had leucopenia to low dose CYC, mycophenolate mofetil and azathioprine were also tried. However, patient developed leukopenia with all the above agents. Initiation of tacrolimus (TAC) was followed by dramatic response: Proteinuria decreased, serum albumin normalized and C‑ANCA and anti‑PR3 ANCA assays became negative. This is the first successful case of TAC as an induction agent in a patient with GPA (ANCA associated vasculitis with renal involvement). [ABSTRACT FROM AUTHOR]