A case of renal involvement in juvenile xanthogranulomatosis

Juvenile xanthogranuloma (JXG) is a type of non-Langerhans cell histiocytosis that rarely involves other than the skin. Here, we present detailed ultrasound (US) findings, including a contrast study, of a rare JXD renal lesion. A 42-year-old woman with JXG had chronic kidney disease. Ultrasound showed multiple cystic masses with fine internal septa in both kidneys. Contrast-enhanced US revealed early staining and late washout consistent with the internal septa inside the masses and led us to suspect cystic renal cell carcinomas in both kidneys. Left nephrectomy was performed for diagnostic purposes. Microscopic examination revealed a foamy component with Touton-type giant cells by histiocytosis; CD68 and S100 were positive, and CD1a was negative, leading the diagnosis of JXD. The US findings of extracutaneous lesions on JXA are variable and can be cystic, and when arising in the kidney may resemble cystic renal cell carcinoma.