Triple-Positive Serology in Rapidly Progressive Glomerulonephritis: A Diagnostic Dilemma.

The acute onset of malignant hypertension and acute kidney injury in patients with features suggestive of systemic sclerosis often raises concern for scleroderma renal crisis, a life-threatening complication requiring prompt recognition and angiotensin-converting enzyme inhibitor therapy. However, other autoimmune vasculitides, including antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis and antiglomerular basement membrane (anti-GBM) disease, can present similarly but require immunosuppressive therapy. We reported a diagnostically challenging case of a 72-year-old woman with interstitial lung disease, Raynaud's phenomenon, and serologic findings of antitopoisomerase I antibody and antimyeloperoxidase (p-ANCA) antibodies. Given this clinical picture, scleroderma renal crisis was initially suspected. However, a kidney biopsy revealed pauci-immune necrotizing and crescentic glomerulonephritis with uniform crescents and without linear IgG deposition along the GBM. Given the uniformity of crescents, additional serologic testing revealed elevated anti-GBM antibody levels, posing a therapeutic dilemma regarding the presence of clinically significant anti-GBM disease in the absence of immunofluorescence confirmation. This case highlighted the critical role of early kidney biopsy in ambiguous presentations and the need for heightened awareness of overlapping autoimmune syndromes to guide timely and appropriate treatment. Systematic reporting of such overlap syndromes is essential for improving diagnostic accuracy and optimizing outcomes.