Significance of psammoma bodies in serous cavity fluid: a cytopathologic analysis.

BACKGROUND

Psammoma bodies (PBs) are encountered only rarely in body cavity fluids (BCF). Although to the authors' knowledge their presence in certain neoplasms (e.g., those of the thyroid, ovary, lung, brain, etc.) is established, their significance in BCF has not been well defined.

METHODS

Diagnoses concerning 3335 BCF samples were reviewed from the cytopathology files for the presence of PBs over an 8-year period. Cytologic preparations included cytospin preparations and Millipore filters stained with the Papanicolaou stain. Clinicopathologic correlation was performed on any subsequent surgical studies.

RESULTS

Of the 3335 BCF samples studies (2444 pleural samples, 688 peritoneal samples, and 203 pericardial samples), PBs were noted in 123 cases (3.7%). Of these 123 cases, 112 were the peritoneal fluid (91%), 10 were the pleural fluid (8.1%), and 1 was in the pericardial fluid (0.81%). All 11 cases of pleural and pericardial effusions with PBs were malignant (carcinomas of the thyroid, lung, and ovary) compared with 62 of 112 peritoneal fluid samples (55.4%) (carcinoma of the ovary and uterus and mesothelioma). Nine of the remaining 50 cases of cytologically benign peritoneal fluids with PBs detected on follow-up tissue biopsy demonstrated peritoneal metastases from ovarian or endometrial carcinoma. Therefore, 41 of 112 cases of peritoneal fluid with PBs remained benign even after clinical follow-up and/or tissue biopsy (36.6%) and demonstrated ovarian cystadenoma/cystadenofibroma, papillary mesothelial hyperplasia, endosalpingiosis, endometriosis, and other miscellaneous benign diagnoses.

CONCLUSIONS

PBs in BCF is a rare finding. Although in the authors' experience their presence in pleural and pericardial effusions signifies carcinomatous involvement, in the current study, peritoneal fluids with PBs were found to be benign in a significant number of cases (36.6%). In the latter scenario and in the absence of an obvious malignancy, attempts should be made to rule out the above-mentioned benign lesions.