Liesegang Rings in Xanthogranulomatous Pyelonephritis: A Case Report

Liesegang rings are concentric noncellular lamellar structures, rarely seen in vivo, occurring as a consequence of the accumulation of insoluble products in a colloidal matrix. These characteristic structures are a rare phenomenon usually found in association with cystic or inflammatory lesions and may be mistaken for parasites. The authors examined Liesegang rings from an inflammatory kidney lesion identified previously as a tumoral lesion on computerized tomography. On microscopic evaluation, Liesegang rings can be mistaken for eggs and larvae of parasites, psammoma bodies and calcification. Special stains like PAS, Grocott, von Kossa and Masson's trichrome facilitate the diagnosis. 1. Introduction Liesegang rings are laminated precipitation structures well recognized in the field of chemistry, occurring as a consequence of the rhythmic accumulation of sub- and supersaturation of insoluble products in a colloidal matrix, which precipitate by diffusion resulting in characteristic precipitation rings. They are recognized only rarely in vivo, arising in association with cystic or inflammatory processes. Clinically reported cases have been described most frequently in the kidney and can be mistaken for parasitic infestations. Other reports include paranasal sinus, breast, eye and peritoneum [1–5]. The rings are characterized by periphoeral concentric layers with radial cross-striations that surround an amorphous, central core. They are usually spherical but can vary in shape and size from 5？nm to 820？nm. Concentric laminated morphology can be accentuated with papanicolaou, hematoxylin-eosin, Diff-Quick, Masson’s trichrome, von Kossa and Gram stains [6–10]. In the present study, the authors describe Liesegang rings associated with xanthogranulomatous pyelonephritis. 2. Case Report A 51-year-old woman was admitted to the hospital complaining from pain in the left upper quadrant of the abdomen for the last month. The abdominal computerized tomography showed a nodular tumor-like lesion on the upper left pole of the kidney. Partial nephrectomy was performed. The surgical specimen weighted 78,0？g and measured 5, , ,5？cm. On gross examination, there was a poorly circumscribed yellow soft nodule with central degeneration, measuring 3, , ,0？cm. Microscopically there was a suppurative chronic intersticial nephritis with a lymphoid and neutrophilic infiltrate, central necrotic zone surrounded by foamy macrophages and giant multinucleated cells, tubular atrophy, periglomerular fibrosis and global glomerular sclerosis. The inflammatory process has extended to the