A 68-year-old man developed rapidly progressive glomerulonephritis due to MPO-ANCA-associated microscopic polyangiitis within 6 months of a diagnosis of seropositive rheumatoid arthritis, emphasising the importance of considering ANCA-associated vasculitis in patients with rheumatoid arthritis who develop acute kidney injury even early in the disease course.
Key Findings
Background
ANCA-associated vasculitis can develop very early in the course of rheumatoid arthritis, contrary to the more common pattern of late-onset vasculitis.
The case involved a 68-year-old man who developed ANCA-associated vasculitis within 6 months of a diagnosis of seropositive rheumatoid arthritis.
The authors note that vasculitis 'more commonly develops several years after rheumatoid arthritis onset,' making this an atypical early presentation.
The coexistence of rheumatoid arthritis and ANCA-associated vasculitis is recognised but this timing was unusual.
Results
The patient presented with rapidly progressive glomerulonephritis caused by myeloperoxidase (MPO)-ANCA-associated microscopic polyangiitis.
Diagnosis was triggered by an acute deterioration in renal function.
The patient was a 68-year-old man with pre-existing seropositive rheumatoid arthritis.
Conclusions
ANCA-associated vasculitis should be considered in rheumatoid arthritis patients who develop acute kidney injury, even early in the disease course.
The authors emphasise the diagnostic challenges posed by coexisting autoimmune conditions.
The case highlights that acute kidney injury in a rheumatoid arthritis patient should prompt investigation for ANCA-associated vasculitis regardless of how recently rheumatoid arthritis was diagnosed.
ANCA-associated vasculitis is described as 'a multisystem autoimmune disease that may present diagnostic challenges, particularly in patients with coexisting autoimmune conditions.'
What This Means
This research describes a case report of a 68-year-old man who was diagnosed with rheumatoid arthritis (an autoimmune joint disease) and then, just six months later, developed a serious kidney condition called rapidly progressive glomerulonephritis. Testing revealed he also had a separate autoimmune condition called ANCA-associated vasculitis — specifically microscopic polyangiitis — which was attacking his kidneys. A kidney biopsy confirmed the diagnosis by showing a characteristic pattern of immune-related kidney damage called pauci-immune necrotising crescentic glomerulonephritis.
This case is notable because ANCA-associated vasculitis typically develops many years after rheumatoid arthritis, not within months. The authors highlight that when someone with rheumatoid arthritis experiences a sudden worsening of kidney function, doctors should consider ANCA-associated vasculitis as a possible cause — even if the rheumatoid arthritis diagnosis is very recent. Early recognition matters because ANCA-associated vasculitis can cause rapid, severe kidney damage if not treated promptly.
This research suggests that clinicians caring for rheumatoid arthritis patients should maintain a high level of suspicion for ANCA-associated vasculitis when those patients develop signs of kidney problems, regardless of how long they have had rheumatoid arthritis. The coexistence of these two autoimmune conditions, while uncommon, can create diagnostic confusion that may delay appropriate treatment.
Sreeneyasan J, Dewar R, Rana S, Choudhury J, Alderson H, Chitale S. (2026). Rapidly progressive glomerulonephritis in rheumatoid arthritis: an early presentation of ANCA-associated vasculitis.. BMJ case reports. https://doi.org/10.1136/bcr-2026-272069