An atypical presentation of microscopic polyangiitis without renal involvement in an older patient with falls, bilateral lower limb swelling and neuropathy.
Sun Wai M, Walker D, Ugwoke A • BMJ case reports • 2026
This case report describes a rare presentation of microscopic polyangiitis with isolated mononeuritis multiplex without glomerulonephritis or other hallmark features, highlighting the varied manifestations of MPA and challenges in recognition, particularly in older adults.
Key Findings
Background
MPA can present atypically with isolated mononeuritis multiplex without glomerulonephritis or other hallmark features.
The case described a rare presentation lacking the almost universally expected glomerulonephritis
The patient presented with falls, bilateral lower limb swelling, and neuropathy
The authors describe this as reflecting 'the varied manifestations of MPA and challenges in recognising the condition'
Background
MPA is a primary systemic small-vessel vasculitis associated with antineutrophil cytoplasmic antibodies (ANCA) that is uncommon in the UK but increases with age.
MPA is classified as a primary systemic small-vessel vasculitis
The condition is 'uncommon among the UK population, although it increases with age'
Glomerulonephritis is described as 'almost always present' in MPA
Background
MPA-related neuropathy damages nerve vasculature and may predispose older adults to falls.
MPA-related neuropathy 'damages nerve vasculature, typically causing mononeuritis multiplex'
This neuropathy 'may predispose older adults to falls'
The patient in this case presented with falls as a feature of their atypical MPA presentation
Background
Treatment complications from immunosuppression for MPA are common in older adults, increase with frailty, and may complicate management.
Treatment involves 'managing the underlying vasculitis through immunosuppression'
Treatment complications 'arising from immunosuppression are common in older adults, increase with frailty and may complicate management'
A multidisciplinary approach is described as necessary, with 'an understanding of the condition from geriatric perspectives' identified as key
Conclusions
Awareness of MPA is essential to timely diagnosis, treatment initiation, and improved health outcomes.
The atypical presentation without renal involvement delayed or challenged recognition of the condition
The authors emphasize that 'awareness of MPA is essential to timely diagnosis, treatment initiation and improved health outcomes'
The case illustrates diagnostic challenges when hallmark features such as glomerulonephritis are absent
Sun Wai M, Walker D, Ugwoke A. (2026). An atypical presentation of microscopic polyangiitis without renal involvement in an older patient with falls, bilateral lower limb swelling and neuropathy.. BMJ case reports. https://doi.org/10.1136/bcr-2025-270153