[Pseudotumor focal xanthogranulomatous pyelonephritis in adults. Role of imaging technics in the diagnosis].

Based on 8 personal cases, pseudo-tumoral xanthogranulomatous pyelonephritis is reviewed with emphasis on diagnosis. The condition is a particular form of chronic renal suppuration of histologic definition (combined lesions of chronic pyelonephritis and xanthogranulomatous foam cells). Two forms are recognized: one diffuse, fairly frequent form corresponding to a pyonephrosis, and a pseudo tumoral focal form, the only type discussed in this report, which raises the problem of diagnosis of a renal mass that requires the application of all currently available exploration means to define its true nature. Intravenous urography, ultrasound and CT scan imaging show a non-specific mass of variable character. Selective renal arteriography sometimes shows inflammatory type vascularization, a valuable aid but again non-specific. Puncture biopsy has been used by few authors. However, the presence of a renal mass associated with a chronic pyelonephritis, lithiasis and recurrent episodes of urinary infection should suggest the diagnosis and make use of imaging techniques to detect the affection and adapt therapy, major oncologic surgery being of no utility. Perhaps NMR imaging will provide a step forward in tissue characterization, but it is too early to say.