Inflammatory pseudotumor of the kidney with extensive metaplastic bone.

Inflammatory pseudotumor (IPT) of the kidney is a very rare lesion. We describe an 8-year-old boy with IPT of the kidney presenting as a single episode of hematuria. The case highlights a new feature, metaplastic bone, not previously described in IPT. This new feature may be helpful in establishing the correct preoperative and histopathologic diagnosis of IPT of kidney and avoiding inappropriately aggressive therapy. Despite its rarity, IPT of the kidney should be kept in mind in the differential diagnosis of a solitary renal mass.