[Renal malacoplakia. A report of a case and discussion]

A woman of 40 years of age without any past history of urinary affections was discovered to have malacoplakia of one kidney, demonstrated by a mass in the right flank, fever, and a coliform urinary infection. No secretion from the affected side was observed on intravenous urography. Renal arteriography showed an inflammatory mass affecting mainly the lower half of the kidney. Histological examination of a nephrectomy specimen led to a diagnosis of a malacoplakia. The authors review the clinical, radiological, and pathological features of renal malacoplakia, which is an inflammatory condition of the renal parenchyma very similar to xantogranulomatous pyelonephritis. The pathogenesis is completely unknown, but the lesion probably arises from a disorder of macrophage function, and renal malacoplakia should be a differential diagnosis of inflammatory renal masses.