Cytologic characteristics of meningeal carcinomatosis: increased diagnostic accuracy using carcinoembryonic antigen and epithelial membrane antigen immunocytochemistry.

BACKGROUND AND OBJECTIVES Traditionally, the diagnosis of meningeal carcinomatosis has been based on clinical suspicion and confirmed by cytologic study of cerebrospinal fluid. However, routine cytologic study may fail to detect malignant cells in a relatively large number of cases. We used immunocytochemistry in an attempt to increase the sensitivity of cytologic detection of malignant neoplasms in cerebrospinal fluid. MATERIALS AND METHODS Thirty-eight consecutive cerebrospinal fluid specimens from patients with clinically suspected meningeal carcinomatosis were selected for this study. Immunocytochemistry for carcinoembryonic antigen and epithelial membrane antigen were used on the archival Papanicolaou-stained cerebrospinal fluid preparations. RESULTS Of the 23 specimens from patients with proven meningeal carcinomatosis, 13 were correctly diagnosed using cytomorphologic criteria alone. The diagnosis of malignant neoplasm in 8 cytologically suspicious and 1 cytologically negative specimen was confirmed using immunocytochemistry. All cases that were negative on follow-up were also negative cytologically and immunocytochemically. CONCLUSIONS We conclude that in using common antibodies, such as carcinoembryonic antigen and epithelial membrane antigen, the sensitivity of the cytologic diagnosis of meningeal carcinomatosis increases, and that previously Papanicolaou-stained preparations are suitable for immunocytochemical studies.