Liesegang-like rings in fine needle aspirates of renal/perirenal hemorrhagic cysts.

Periodic structures with equally spaced radial striations, identified as Liesegang-like rings, were encountered in fine needle aspirates of two patients' hemorrhagic renal/perirenal cysts. The patients, one 60 and the other 39 years old, had acute right-flank pain; both underwent nephrectomy. The ring structures ranged in size from 8 microns to 200 microns in diameter and had regularly striated double walls. Histochemical and immunoperoxidase tests for iron, calcium, mucopolysaccharides, amyloid, keratin and hemoglobin performed on the tissue sections of the resected specimens gave negative results. With electron microscopy, the ring structures of one of the cases displayed a fine fibrillary composition. Since these Liesegang-like structures may be mistaken for parasites or necrotic tissue, pathologists should be aware of them. To our knowledge, this is the first report of Liesegang-like rings in the cytology literature.