Cytologic findings of psammocarcinoma in peritoneal washings

To describe the cytomorphology of psammocarcinomas in peritoneal washings, including ThinPrep (Cytyc Corporation/Hologic, Marlborough, Massachusetts, U.S.A.)-processed material, in a series of patients.

A retrospective, 19-year search was performed for cases of peritoneal washings in which psammomatous calcifications were reported. All clinical findings as well as cytospin, ThinPrep and cell block slides from peritoneal washings in patients with psammocarcinoma were reviewed.

A total of 37 cases were identified with peritoneal washings containing psammomatous calcifications, 4 (11%) of which were associated with psammocarcinoma. Psammocarcinomas occurred in patients of average age 52 years (range, 39-68) and were of either peritoneal (n = 3) or ovarian (n = 1) origin. In these psammocarcinomas, peritoneal washings were bloody, were of moderate to high cellularity and contained many papillary serous cell groups. Tumor cells had high nuclear:cytoplasmic ratios, irregular nuclei, prominent nucleoli and variable hyperchromasia. Laminated psammomatous calcifications were abundant in 3 cases (> 80 bodies per cytologic slide and cell block) and of variable size (up to 150 microm), occurring both alone and in clusters associated with atypical epithelial cell groups.

The characteristic cytologic finding of low grade epithelial atypia in papillary cell groups accompanied by numerous psammoma bodies is very distinctive of psammocarcinoma and closely resembles the striking histopathologic findings seen in this rare subset of serous carcinomas.