전신홍반루푸스환자에서 소변검사에서 이상소견이 발생한 경우에는 루푸스 신염뿐만 아니라 드물게 IgA 신증을 포함한 비루푸스 신염의 경우도 있으므로, 이를 염두에 두어 신장 조직검사로 정확한 진단을 하여 적절한 치료방법을 결정하는 것이 중요하겠다.

Renal involvement is frequently seen in patients with systemic lupus erythematosus (SLE). The occurrence of non-lupus nephritis, and especially IgA nephropathy, in SLE patients has rarely been reported. We describe here the case of a 30-year-old woman who had systemic lupus erythematosus and nontuberculous mycobacterial lung disease, and her biopsy of a renal lesion was unexpectedly diagnostic of IgA nephropathy. Although both IgA nephropathy and lupus nephritis are immune complex mediated diseases, their laboratory and histopathologic findings and the extra-renal clinical manifestations are different and these all support a different pathogenesis for the 2 diseases. Renal biopsy plays a crucial role in identifying and diagnosing renal lesions, which may have prognostic and therapeutic implications that are distinct from those of lupus nephritis. In conclusion, performing a renal biopsy in SLE patients who have urinary abnormalities is important since a correct diagnosis would permit the most appropriate treatment to be started and so avoid unnecessary immunosuppressive treatments.