Xanthogranulomatous pyelonephritis. A reappraisal and immunohistochemical study

The clinicopathologic features of 17 patients with xanthogranulomatous pyelonephritis are described, together with results on a number of histochemical and immunohistochemical techniques that were used to demonstrate the variety of cells involved. Based on our clinicopathologic data and review of the literature, we believe that xanthogranulomatous pyelonephritis should be regarded as a destructive, and, at times, tumefactive inflammatory process that may complicate chronic pyelonephritis. The initiation of this process remains an enigma. However, there appears to be three main features that are associated with xanthogranulomatous pyelonephritis: pelvicalyceal obstruction, ulceration of the pelvicalyceal urothelium, and bacterial infection.