RESUMEN
INTRODUCTION: Lupus nephritis requires antinuclear antibodies as classification criteria. There is a group of patients with nephrotic syndrome and conclusive histopathological findings for lupus nephritis, without classification criteria for systemic lupus erythematosus (SLE) or extrarenal manifestations. These groups of patients have been described as "lupus-like" nephritis or "renal-limited lupus nephritis". METHODS: Renal biopsy with histopathological evaluation with "full-house" immune-reactants in patients with negative antinuclear antibodies. RESULTS: We report four cases with nephrotic syndrome and one with hematuria-proteinuria syndrome: two with impaired glomerular filtration rate and three with preserved renal function; urinary sediment with hematuria without dysmorphia and without extrarenal manifestations for autoimmune disease, negative antinuclear antibodies (ANA) and anti-double stranded DNA (anti-dsDNA); normal C3 and C4 complement levels. Renal biopsy in all cases was consistent for lupus nephritis class V. All patients received treatment as lupus nephritis protocol; only one case received induction with cyclophosphamide and methylprednisolone boluses, the rest received mycophenolic acid and prednisone as induction and maintenance. Two of the cases induced with mycophenolic acid relapsed, requiring cyclophosphamide for 6 months, achieving complete remission. All patients received renin-angiotensin-aldosterone system blockade and hydroxychloroquine. At follow-up, 4 cases still have negative antibodies and are without extrarenal manifestations for SLE classification criteria. The other case, during pregnancy several years after initial diagnosis, had preeclampsia with nephrotic proteinuria and a new determination of positive ANA and anti-dsDNA antibodies, complement levels below normal limits. CONCLUSION: The follow-up of patients with membranous glomerulopathy must be close; lupus like nephritis may be the first manifestation of the disease.