Background/Purpose: Class II mesangial proliferative lupus nephritis has generally been considered a mild form of the condition, with a good response to glucocorticoid treatment. However, some recent studies have questioned this assumption after observing high rates of recurrence and histological transformation to more serious classes. Our aim was to analyse the baseline clinical features and clinical response at one year after treatment in patients with mesangial proliferative lupus nephritis (MPLN) identified at their first renal biopsy.

Methods: The sample comprised 243 patients with SLE treated between 1980 and 2013 at a tertiary university hospital that does not attend pediatric populations. Patients were registered in a specific database (ACHILLES Project). Patients with renal biopsy-confirmed MPLN according to the WHO classification (created in 1982 and modified in 1995, in use until 2004) or the ISN/RPS classification (in use since 2004) were selected for analysis. Data were collected ambispectively. Patients who presented remission (partial or complete) after completing induction therapy were considered “responders”. “Non-responders” were those who presented “no response” (complete or partial absence of response of renal disease after completing induction therapy), class transformation or death due to lupus nephritis.

Results: Forty-five patients (36 women) were identified with a mean age (SD) at the time of diagnosis of nephritis of 39.5 (12.3) years. The median time between diagnosis of SLE and the development of nephritis was 33 months. Proteinuria above 0.5 g/24h was found in 42 (93%) patients, hematuria in 31 (69%), cylindruria in one (2%), mild renal insufficiency in two (4%), and hypocomplementemia in 22 (49%). Mean proteinuria was 1.62 (1.03) g/24 h.

Eight patients had nephrotic syndrome (17%) at the time of diagnosis or during follow-up, excluding patients with nephrotic range proteinuria undergoing class transformation. In the diagnostic biopsy, the mean activity index was 2.09 (1.6) and the chronicity index 0.5 (1.8).

All patients were treated with prednisone (dose 0.5 to 1 mg/kg/day). Thirty-three patients (73%) also received treatment with hydroxychloroquine.

At one year after biopsy, 30 (67%) patients achieved complete remission, seven (16%) partial remission and eight (17%) were non-responders. In six of the eight non-responders a second renal biopsy showed transformation to a higher grade of nephritis (class IV in three cases and class V in the other three), resulting in poor renal and poor overall outcome (one of these patients died at six months of follow-up due to SLE lupus activity in the context of transformation to class IV).

Conclusion: In our cohort of patients with MPLN, the rate of non-responders at one year following treatment reached 17%, and was associated with a high rate of transformation to higher grade nephritis. Our data highlight that renal biopsy should be repeated early in patients who fail to respond to glucocorticoid treatment in order to identify those who may require intense immunosuppressive therapy.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/rate-of-histological-transformation-to-higher-grade-nephritis-in-class-ii-mesangial-proliferative-lupus-glomerulonephritis/