Pediatric idiopathic retroperitoneal fibrosis

Abstract

Retroperitoneal fibrosis (RPF) is a very rare disease that is even more rare in the pediatric population. Even less common are idiopathic pediatric cases of retroperitoneal fibrosis, with a majority of reported pediatric retroperitoneal fibrosis cases being associated with secondary etiologies. We present an 11-year-old Caucasian female that was diagnosed with idiopathic retroperitoneal fibrosis using magnetic resonance imaging (MRI) to work-up severe bilateral hydronephrosis that was identified with retroperitoneal ultrasound. Given the uncommon nature of this serious condition, we present this case to illustrate the importance for physicians to include retroperitoneal fibrosis in the differential diagnosis of a pediatric patient presenting with obstructive urinary findings and understand the utility of using MRI to diagnosis and monitor this disease.

Keywords: Idiopathic retroperitoneal fibrosis; MRI; Pediatric.

Fig. 1

Ultrasound shows marked hydronephrosis bilaterally with relatively preserved cortical thickness.

Fig. 2

Initial MRI: Coronal T2 demonstrates bilateral hydronephrosis and hydroureter (A). Ureters were no longer visualized at the level of the iliacs (B). Axial T1 vibe images demonstrate a nonmass-like soft tissue collar (arrow) surrounding the distal aorta (C), and along the bilateral iliac arteries (D).

Fig. 3

Hematoxylin and Eosin stained section of retroperitoneal soft tissue (A) displays dense fibrosis with admixed inflammation at 100× magnification. Increased magnification to 400× (B) reveals inflammatory infiltrate composed of lymphocytes, plasma cells, histiocytes, and rare eosinophils.

Fig. 4

Initial imaging (A) demonstrates a soft tissue collar around the distal aorta, which demonstrated a significant decrease of soft tissue as demonstrated on initial follow-up imaging 2 months later (B).