Is chronic cutaneous discoid lupus protective against severe renal disease in patients with systemic lupus erythematosus?

Objective: The aim was to assess the level of systemic involvement and character of renal disease in patients with chronic cutaneous lupus erythematosus of the discoid lupus variety (hereafter referred to as 'discoid lupus') and features of systemic lupus erythematosus (SLE). Clinical confusion with other types of cutaneous lupus erythematosus complicates interpretation of some previously reported studies. Methods: Over three years, sixteen patients met the diagnostic criteria of discoid lupus, positive anti-nuclear-antibody, and at least one extracutaneous manifestation. Results: Most patients (14/16) were female, between 26 to 66 years old. Arthritis was the most common extracutaneous manifestation followed by Raynaud's phenomenon. The anti-nuclear-antibody was speckled in ten patients with titers ranging from 1:40 to 1:1280 IU/mL. Elevated levels of double-stranded-DNA in low titers were found in four patients, anti-Smith-antibody in four; anti-Sjogren-syndrome-A-anti-body in seven, and anti-ribonucleoprotein-antibody in seven. Renal function markers were transiently high in some patients but normalized over time. Hematuria and/or proteinuria were present at some time in seven patients. The highest BUN and creatinine levels were 42 mg/dL and 1.5 mg/dL, respectively. One patient had membranous glomerulonephropathy class 5; however, discoid lupus developed well after the onset of renal disease during a time when renal function had returned to normal. Conclusion: Our observational data supports previous reports suggesting that patients with active discoid lupus rarely have progressive renal insufficiency. The mechanism for the development of discoid lupus may involve an immunologic mechanism that differs from that which produces severe organ involvement, especially advanced immune-complex-mediated renal disease. Patients with discoid lupus rarely have sustained high levels of antibodies to double-stranded-DNA. Discoid lupus appears to be a marker for a more benign lupus course. This clinical observation lays the groundwork for a larger prospective, longitudinal cohort study for further validation.