Which one of the following statements is false with regard to Xanthogranulomatous pyelonephritis in children –

Xanthogranulomatous pyelonephritis is a form of chronic pyelonephritis characterised by destruction of renal parenchyma and the presence of granulomas, abscesses and collection of lipid laden foamy macrophages (foam cells). Xanthogranulomatous pyelonephritis in children Age of presentation ranges from infancy to 16 years. Focal form being more common in children --> Appear healthy. Those who affected diffusely, present with non-specific symptoms of chronic infection. i) Weight loss               ii) Fever                 iii) Lethargy         iv) Failure to thrive Proteus is the most common causative organism. I am not sure about option 'c'. In old ages, xanthogranulomatous pyelonephritis is more common in female, but I cound not find data in children.