Clinical phenotypes and long-term outcome of kidney involvement in Erdheim-Chester histiocytosis

Erdheim-Chester disease (ECD) is a rare non-Langerhans cell histiocytosis that frequently infiltrates the peri-kidney space ("hairy kidney" appearance), kidney pelvis and proximal ureters, leading to obstructive uropathy. Here, we analyzed the clinical characteristics, imaging findings and long-term kidney outcome of a large multicenter cohort comprising 195 consecutive patients with ECD. Retroperitoneal peri-kidney or peri-ureteral involvement was detected at diagnosis in 147 patients. Of them, 70 had hydronephrosis (bilateral in 47), and 16 with kidney atrophy (unilateral in 14). Kidney vascular peduncle infiltration was found in 60 patients, and kidney artery stenosis in 31. The estimated glomerular filtration rate (eGFR) at diagnosis was significantly lower in patients with than in those without peri-kidney involvement (median 74 vs. 98 mL/min/1.73 m