Hidden face of lupus nephritis exposed: Isolated tubulointerstitial lupus nephritis.

Implication for health policy/practice/research/medical education: Systemic lupus erythematosus (SLE) is a common multisystemic immunological disorder with protean manifestations. It commonly involves the kidney, which is associated with significant morbidity and mortality. In the kidney, it typically affects glomeruli and blood vessels with secondary involvement of tubulointer-stitial component. Isolated or predominant tubulointerstitial nephritis is exceedingly rare. It is essential to recognize this rare presentation of lupus nephritis, as it has significantly better outcome. Please cite this paper as: Mubarak M. Hidden face of lupus nephritis exposed: Isolated tubulointerstitial lupus nephritis. Commentary ystemic lupus erythematosus (SLE) is a common multisystemic immunological disorder with protean manifestations (1). It may involve any organ of the body, but has predilection for certain organs and systems including the joints, skin, serosal membranes and the kidney. Kidney involvement in SLE is fairly common and is of considerable importance to the practicing nephrologists. This complication is a serious disease with guarded prognosis if not treated promptly and judiciously. Its treatment is potentially toxic, prolonged and difficult to plan and carry out (2). Within individual organs or systems, SLE often involves more than one tissue components in variable combinations, resulting in the heteroge-neity of the pathological lesions and the clinical presentations (1). Involvement of the kidney best illustrates this phenomenon. The disease preferentially targets the glomeruli and the blood vessels , but also frequently involves the tubulointer-stitial component (1, 2). Isolated or predominant involvement of any single tissue element is very rare (3-6). The case report by Ali et al. (7) in this issue of J Nephropathology highlights several important points regarding this rare presentation of lupus nephritis (LN). Indeed, most literature and the classification systems focus on the glo-merular involvement in LN (8). However, from long-term prognostic point of view, it is the tu-bulointerstitial involvement that is more important (2). The extent and the chronicity of the pro