Renal biopsy remains central to diagnosis, prognosis and potentially drug selection in ANCA-associated vasculitis (AAV) and cannot yet be replaced by biomarkers, a leading expert argued at EULAR 2026 in London last week.
Guideline-recommended histological assessment distinguishes AAV from immune complex-mediated diseases such as lupus nephritis, said Professor David Jayne, professor of clinical autoimmunity at the University of Cambridge.
Biopsy confirmed diagnosis, removed clinical uncertainty and excluded other causes, he said, noting that co-occurring pathologies and mimics could not be reliably ruled out with blood or urine biomarkers alone.
“You should be aware that there are many co-occurrences of multiple pathologies, and you want to exclude mimics and secondary causes,” he told delegates.
Unlike biomarkers, biopsy allowed clinicians to assess all key renal compartments, each carrying diagnostic and prognostic significance. Repeat biopsy also had a role in assessing persisting disease activity or relapse in the absence of reliable monitoring biomarkers.
Professor Jayne acknowledged he had recently co-authored research exploring when biopsy could be avoided in patients with highly compatible clinical presentation and high-titre ANCA positivity, but cautioned the approach depended on specialist expertise.
“If you are a general physician, interpreting a compatible presentation can be very difficult,” he said.
The case for biomarkers
Taking the opposing view, Professor Alessandro Tomelleri, consultant immunologist and rheumatologist at IRCCS San Raffaele Hospital in Milan, questioned whether biopsy should remain central to AAV management, citing patient preference, procedural risk and the promise of biomarker-driven monitoring.
Biopsy was invasive and carried a mortality risk of around 0.06%, equivalent to roughly one death per 1,600 procedures, he said, comparing the risk unfavourably to recreational scuba diving.
Survey data from patients with liver disease showed most preferred non-invasive FibroScan over biopsy, he noted.
The feasibility of repeat biopsy was also questionable, Professor Tomelleri argued. With up to 40% of AAV patients developing new or recurrent renal involvement over 10 years, and most patients safely able to undergo only one or two biopsies in a lifetime, a repeatable non-invasive alternative was needed.
He pointed to urinary biomarkers including CD163 and MCP-1 for disease activity and EGF for chronic damage, which combined with clinical features, ANCA positivity, active urinary sediment and imaging could enable diagnosis, risk stratification and monitoring without biopsy.
Hepatology had already made this shift, moving from serial biopsies to non-invasive monitoring, and nephrology should follow, he argued.
“Why expose a patient to the risk of a dangerous procedure when the urine holds the answers?” he said.