Ossifying renal tumor of infancy
 Discussion of Ossifying renal tumor of infancy
- Rare benign renal mass, with only approximately 11 cases reported in the literature.
- Patients have ranged in age from 6 days to 14 months.
- The mass is believed to arise from urothelium and is attached to the renal medulla, specifically the papillary region of the renal pyramids. From this location, it extends in a polypoid fashion into the collecting system.
- At microscopic analysis, the lesion consists of three basic components: an osteoid core, osteoblasts, and spindle cells.
- The origin and natural history of the lesion are uncertain.
- Biologic behavior of ossifying renal tumor of infancy appears to be benign, with no reported cases of malignant spread and postsurgical disease-free survival at follow-up lasting from 4 months to 23 years.
 Imaging Findings for Ossifying renal tumor of infancy
- At imaging, the renal outline is usually maintained; however, filling defects with partial obstruction of the collecting system are often seen.
- Because of its location within the collecting system and its characteristic ossification, ossifying renal tumor of infancy may mimic a staghorn calculus, which would be exceedingly rare in the age group in which this lesion occurs.
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 References for Ossifying renal tumor of infancy
- Lisa H. Lowe, Bernardo H. Isuani, Richard M. Heller, Sharon M. Stein, Joyce E. Johnson, Oscar M. Navarro, and Marta Hernanz-Schulman. Pediatric Renal Masses: Wilms Tumor and Beyond. RadioGraphics 2000 20: 1585-1603.