Biopsy utility in the workup of ANCA-associated vasculitis

ANCA - associated Vasculitis (AAV) positive biopsy is supportive of vasculitis diagnosis, the aim of this manuscript is that renal biopsy is not always compulsory in the diagnosis and management of AAV. 79 years old, Caucasian women, admitted with AAV suspicion, MPO positive. A Microscopic polyangiitis with a pulmonary – renal syndrome was diagnosed after other AAV were excluded. Remission induction and maintenance therapy was made. In 6 months the patient presented a considerable improvement with lower MPO value, ESR and a stabilization of kidney function. Renal biopsy has to be performed in the majority of patients with the suspicion or renal AAV, although in this case it was not performed considering that the patient was on chronic anticoagulation and renal biopsy was not essential for the diagnosis. We suggest that renal biopsy is a valuable method in establishes the aetiology of kidney disease and that it could be dismissed in AAV with suggestive clinical presentation and low suspicion for secondary vasculitis.