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Kidney involvement in vasculitis associated with antineutrophil cytoplasmic antibodies (ANCA) is characterized by the presence of pauci-immune glomerulonephritis with crescent formation. However, this manifestation can also be found in severe cases of lupus nephritis (NL). Although 20% of patients with systemic lupus erythematosus (SLE) test positive for ANCA, cases have been described where patients meet classification criteria for both entities, known as overlap syndrome, which is extremely rare.
Objective: To report the case of a woman with SLE, positive p-ANCA antibodies, and kidney activity.
Case Presentation: A 25-year-old woman with a history of preeclampsia in her first pregnancy at the age of 12 subsequently developed systemic arterial hypertension without medical follow-up. She was admitted to the internal medicine service due to unintentional weight loss and uremic syndrome characterized by nausea and oral intolerance. She met the criteria for dialysis urgency due to metabolic acidosis and hyperkalemia refractory to treatment, so renal replacement therapy was initiated through hemodialysis. An immunological profile was requested, obtaining ANAs 1:160 fine speckled pattern, complement C3 88.7, C4 25.6, anti-DNA ds antibodies 10.2 Ul/ml, anti-RO 52 and Ro 60 negative, anti-RNP antibodies negative, anti-sm antibodies negative, p-ANCA 1:80, anti-myeloperoxidase (MPO) antibodies 99.03 UR/mL, Anti-proteinase-3 <2. The diagnosis was concluded as systemic lupus erythematosus ACR/EULAR 2019 10 points, SLEDAI-2k 16 points. During her stay, a kidney biopsy was performed, which reported the presence of scarred extracapillary lesions (fibrous crescents) in most of the glomeruli, concluding: Endocapillary proliferative glomerulonephritis by immune complexes with fibrous extracapillary lesions and advanced global and segmental sclerosis. IgG positive 2+, IgA negative, IgM positive 2+, C3c positive 3+, c1q positive 2+, c4c negative, Kappa positive 2+, Lambda positive 3+. Chronicity index 8/12. Treatment with methylprednisolone 1gr/day in 3 doses and mycophenolate 1gr/day (Figure1) was indicated. The patient was discharged home requiring renal replacement therapy through peritoneal dialysis.
The presence of ANCA antibodies in patients with SLE could indicate the existence of an overlap syndrome. In the case of the previously mentioned patient, she did not meet diagnostic criteria for vasculitis, and the kidney biopsy reported findings more compatible with NL (presence of immune complexes) than with vasculitis. Therefore, despite the positivity of anti-MPO antibodies, it is not considered that she had an overlap syndrome, and this phenomenon can be observed in drug-induced SLE and in NL. Therefore, it is recommended to deliberately search for ANCA in every patient with SLE as it could be established as a predisposing factor for the development of NL. The evidence of overlap syndrome is mainly based on case reports suggesting that this condition tends to show aggressive behavior with adverse outcomes.