Development of IgA nephritis following cat scratch disease in a 13-year-old boy.

We describe a 13-year-old boy who presented with hematuria and intermittent low-grade proteinuria at the time when he was diagnosed with cat scratch disease. Two months before presentation, he had a negative urinalysis during a routine physical evaluation. He continued to have microscopic hematuria for the next 6 months, when he developed gross hematuria and recurrence of low-grade proteinuria. The renal biopsy showed evidence of mild/moderate IgA nephropathy. We speculate that the immunological changes associated with cat scratch disease in this patient may have triggered the development of IgA nephropathy. A history or serological evidence of infection with Bartonella henselae may need to be sought in patients presenting with IgA nephritis.