Overview
Systemic lupus erythematosus (SLE) is a chronic autoimmune disease classified by specific clinical and immunological criteria 1. Lupus nephritis (LN) is a common and serious manifestation of SLE, characterized by glomerular lesions that are pathologically classified 2. The International Society of Nephrology/Renal Pathology Society (ISN/RPS) classification includes various classes of LN, with Class III referring to focal lupus nephritis 2.Diagnosis
Diagnosis of SLE requires a positive antinuclear antibody (ANA) at least once as an obligatory entry criterion 1.
Following ANA positivity, patients accumulate points from additive weighted criteria across seven clinical (constitutional, haematological, neuropsychiatric, mucocutaneous, serosal, musculoskeletal, renal) and three immunological (antiphospholipid antibodies, complement proteins, SLE-specific antibodies) domains 1.
A score of ≥10 points classifies a patient as having SLE 1.
Lupus nephritis classification involves revised definitions for glomerular lesions, including mesangial hypercellularity, cellular, fibrocellular, and fibrous crescents, and endocapillary hypercellularity 2.
The terms "endocapillary proliferation" and the class IV-S and IV-G subdivisions of class IV lupus nephritis have been eliminated 2.
Activity and chronicity indices should be applied to all classes of lupus nephritis, replacing the active and chronic designations previously used for class III/IV lesions 2.
The activity index for lupus nephritis now includes fibrinoid necrosis as a specific descriptor 2.Key Recommendations
The 2019 EULAR/ACR classification criteria for SLE require a positive ANA at least once as an obligatory entry criterion 1. (Evidence: Strong)
Classification of SLE requires accumulating ≥10 points from additive weighted criteria across seven clinical and three immunological domains, including renal involvement 1. (Evidence: Strong)
The ISN/RPS classification for lupus nephritis should incorporate revised definitions for glomerular lesions, including mesangial hypercellularity, cellular/fibrocellular/fibrous crescents, and endocapillary hypercellularity 2. (Evidence: Expert opinion)
The terms "endocapillary proliferation" and the class IV-S and IV-G subdivisions of class IV lupus nephritis should be eliminated 2. (Evidence: Expert opinion)
Activity and chronicity indices should be applied to all classes of lupus nephritis, replacing the active and chronic designations for class III/IV lesions 2. (Evidence: Expert opinion)
Fibrinoid necrosis should be included as a specific descriptor in the activity index for lupus nephritis 2. (Evidence: Expert opinion)References
1 Aringer M, Costenbader K, Daikh D, Brinks R, Mosca M, Ramsey-Goldman R et al.. 2019 European League Against Rheumatism/American College of Rheumatology classification criteria for systemic lupus erythematosus. Annals of the rheumatic diseases 2019. link
2 Bajema IM, Wilhelmus S, Alpers CE, Bruijn JA, Colvin RB, Cook HT et al.. Revision of the International Society of Nephrology/Renal Pathology Society classification for lupus nephritis: clarification of definitions, and modified National Institutes of Health activity and chronicity indices. Kidney international 2018. link