Tubulointerstitial lupus nephritis.

BACKGROUND Isolated or predominant tubulointerstitial lupus nephritis is rare. CASE PRESENTATION Here we report the case of a thirty eight years old male who was diagnosed with systemic lupus erythematosus (SLE) according to clinical and laboratory criteria and presented with impaired renal function and non nephrotic range proteinuria. Renal biopsy revealed normal glomeruli but interstitial momonuclear cell infiltration. Immunohiostochemistry (IHC) showed immune deposits in the tubular basement membranes (TBMs), and the peritubular capillary basement membranes (PTCBMs). He was started on high dose oral steroids, which were gradually tapered over one month. His renal functions improved over few days and normalized by the end of the first month of treatment. He was continued on low dose steroids and azathioprine with no evidence of relapse. CONCLUSIONS Predominant tubulointerstitial lupus can occur, although rarely; and it runs a favorable course with good response to treatment.