Diagnosis and Management of Seronegative Lupus Nephritis

Diagnostic Criteria

The presence of "full house" immune complex deposition (IgG, IgM, IgA, C3, C1q) on immunofluorescence staining is a strong indicator of lupus nephritis, even in the absence of extrarenal manifestations or positive serology, according to the Kidney Disease: Improving Global Outcomes (KDIGO) guidelines 1, 2
The absence of capillary proliferation on renal biopsy helps to exclude other forms of proliferative glomerulonephritis 3, 2
A patient's age of 13 is consistent with lupus nephritis in children, although it is more commonly seen in females 1

According to the KDIGO 2021 guidelines, when encountering immune complex deposition with a "full house pattern", other causes should be excluded in the following order 3, 2:

The American College of Rheumatology recommends treating seronegative lupus nephritis as Class IV lupus nephritis according to KDIGO 2012 guidelines 1
Initial treatment includes high-dose corticosteroids combined with cyclophosphamide or mycophenolate mofetil (MMF) 1
Corticosteroid dosage: methylprednisolone 500-1000mg IV for 3 days, followed by prednisone 1mg/kg/day (maximum 60mg) for at least 4 weeks 1
Cyclophosphamide is preferred over MMF in severe cases (with fibrinoid necrosis, crescents, or rapidly progressive glomerulonephritis) 1

After 3-6 months of initial treatment, switch to azathioprine or MMF combined with low-dose corticosteroids, maintaining for at least 18 months 6
Regular monitoring of proteinuria and renal function is necessary - a decrease of ≥40% in eGFR over 2-3 years is a poor prognostic sign 6