ANCA-associated vasculitis overlaps with systemic sclerosis: a case report and literature review.

Background Systemic sclerosis (SSc) and anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) both affect the kidney and may cause renal failure. Treatment of AAV is dramatically different from that of SSc renal crisis (SRC). Kidney biopsy is not recommended for diagnosing SRC, but it is the only reliable diagnostic method for AAV. Case presentation Here, a 49-year-old male patient with diffuse SSc presented with acute renal insufficiency and detectable ANCA with myeloperoxidase-specific antibodies. A renal biopsy revealed necrotizing glomerulonephritis and was consistent with AAV. This finding confirms the existence of AAV and SSc overlap syndrome. The patient was treated with intravenous methylprednisolone, intravenous cyclophosphamide, tandem membrane plasma exchange, and hemodialysis. After treatment, his clinical symptoms remained stable, and his creatinine and C-reactive protein (CRP) levels have remained normalized as of his most recent follow-up after hospital discharge. Conclusions AAV can overlap with SSc; although this condition is rare, it is associated with considerable morbidity and mortality. Therefore, it is critical to recognize AAV in the setting of worsening renal function due to SSs and provide appropriate treatment. Several clinical features are suggestive of AAV rather than SRC, but renal biopsy is required for accurate diagnosis.