Background: Lupus membranous glomerulonephritis (LMG) is sometimes difficult to distinguish from idiopathic membranous glomerulonephritis (IMG) and little is known about its natural history.
Methods: We have performed a retrospective study of 16 patients with LMG, types Va ("pure" LMG) (8 patients) and Vb (mesangial proliferation) (8 patients). Analytical and clinical characteristics were analyzed in each case at the onset of the disease and during follow-up.
Results: At the time of diagnosis, 7 patients (43%) did not present any extrarenal manifestations of systemic lupus erythematosus (SLE). Nephrotic syndrome was the most common clinical presentation (81%). 14 patients (87%) showed positive antinuclear antibodies (ANA), but at low titres (< 1/300); anti-DNA antibodies were positive only in 3 cases (18%) and hypocomplementemia was observed in 2 (12%). The most relevant histological findings were the presence of Clq deposits (83%) and subendothelial and mesangial deposits. Treatment consisted of corticosteroids, adding immunosuppression when no response was obtained in 2-3 months. In recent years, an angiotensin-converting enzyme inhibitor (ACEI) was added before immunosuppression. At the end of the study, 6 patients (42%) developed chronic renal insufficiency and 8 (58%) renainea with normal renal function. Actuarial renal survival was 100% at 5 years and 75% at 10 years. The evolution towards a non-nephrotic range proteinuria throughout the follow-up was the only parameter significantly associated with a good prognosis.
Conclusions: LMG can present without extra-renal symptoms of SLE and even with very poor expression of its serological markers. Almost half of the patients (42%) developed chronic renal insufficiency. The evolution towards a non-nephrotic range proteinuria correlated with the maintenance of a normal renal function.