Lupus nephritis: histopathologic features, classification and histologic scoring in renal biopsy

Lupus nephritis (LN) is one of the most significant manifestations in systemic lupus erythematosus (SLE), although in some cases there is no direct correlation among clinical, serologic and histologic findings. Therefore, renal biopsy and histopathologic classification by the activity and chronicity assessment of LN are considered necessary before the initiation of the treatment. In this paper 311 renal biopsies in patients with LN were analyzed and classified according to the WHO Classification published in 1974. Renal biopsy specimens were routinely processed for standard analysis by light microscopy (LM), immunofluorescent (IF), and electron microscopy (EM). Biopsy findings were compared with the common clinical symptoms. It is important to recognize that histopathologic lesions in the analyzed tissue might precede the symptoms and clinical manifestations, and therefore are an important factor in the appropriate therapeutic approach. Histopathological assessment of the class of LN represents an important predictor in most patients because the lesions of LN class I and class II most often have no progression and consequently do not require an aggressive treatment. Diffuse proliferative glomerulonephritis (class IV) as a severe form of renal lesion requires the application of high doses of corticosteroids and cytotoxic medicaments. The established quantitive indexes have significant predictive value. Activity index (AI) evaluates the presence of fresh inflammatory and potentially reversible lesions and chronicity index (CI) evaluate the presence of irreversible glomerular lesions such as sclerosis, tubular atrophy, interstitial fibrosis, etc. High AI and low CI, particularly in the class IV of LN, suggest the necessity of an aggressive treatment of the inflammatory process aiming to preserve the renal function. High CI and low AI characterize irreversible sclerosing lesions, where an aggressive treatment is considered unnecessary. Our experience suggests the necessity of introducing the new morphologic elements into the activity and chronicity scoring system which would correlate better the clinical symptoms. This should provide higher reliability of scoring, since it evaluates important elements in clinical-morphologic diagnosis of LN.