Scleroderma and the Kidney: Not just Renal Crisis
Not all renal failure in scleroderma is HTN related renal crisis. While renal TMA and endothelial damage is a common cause of AKI in scleroderma, other interesting cause to keep in mind is vasculitis.
Of all the vasculitides, small vessel ANCA vasculitis is noted to be seen with scleroderma.
A study by Rho et al. found 31 reports containing 63 cases of ANCA vasculitis with scleroderma up to 1994. Fifty of the 63 cases provided sufficient clinical and laboratory information and were included in the analysis. Eighty-four percent were women with a mean age of 57.1 years. Over 70% had ANA positive and 70% with anti-Scl-70 antibody, and 72% with positive anti-MPO antibody. The most common end-organ involvement included kidneys (82%) and lungs (70% had pulmonary fibrosis). Mortality was highest in the first year.
A more recent review has 11 more cases that also were reported. Most were females, all had anti MPO titers and 9 /11 cases had renal involvement with crescentic GN.
These findings highlight the importance of considering crescentic GN related to ANCA vasculitis as a potential cause of renal insufficiency in scleroderma. Classically, scleroderma renal crisis occurs in up to 20% of patients with diffuse scleroderma, and renal involvement manifesting as hypertension, proteinuria, or azotemia can be found in 45–60%. However, causes other than scleroderma renal crisis should be considered as a differential diagnosis, especially in settings of normal blood pressure or ANCA positivity.