Malignant fibrous histiocytoma arising from the renal capsule.

Malignant fibrous histiocytoma (MFH) arising from the renal capsule is a rare tumor. We report a case of 55-year-old man with this tumor. Radiological imaging, including magnetic resonance (MR) imaging, was helpful in the differential diagnosis between MFH of the renal capsule and other renal tumors. In particular, a hypo-intense area identified on T(2)-weighted images reflecting the fibrous component was identified as an important characteristic of renal MFH.