MORPHOLOGY AND PATHOGENESIS OF LIESEGANG RINGS IN CYST ASPIRATES - REPORT OF 2 CASES WITH ANCILLARY STUDIES

Liesegang rings are laminated ring-like structures occasionally found in benign cysts and abscesses. They have been confused with parasites (especially eggs), algae, calcifications and psammoma bodies. We exami ned Liesegang rings from fine-needle aspiration (FNA) biopsies of a be nign cost of the breast and a complex renal cyst. Liesegang rings were best observed with Papanicolaou, hematoxylin-eosin, Masson's trichrom e, acid-fast (AFB), and cram stains, which accentuate the concentrical ly laminated morphology An amorphous electron-dense core and fibrillar y lucent concentric rings were seen with transmission electron microsc opy with no significant energy peaks by electron probe microanalysis o r distinct diffraction patterns by X-ray diffraction. This investigati on indicates that Liesegang rings are composed of organic substances m ost likely formed by periodic precipitation from a supersaturated solu tion within cystic fluid. Awareness of the Liesegang phenomenon within cystic lesions will decrease the possibility of erroneous misdiagnosi s as another type of pathologic process. Diagn. Cytopathol. 1998;19:11 6-119. (C) 1998 Wiley-Liss, Inc.