Cystic brain lesions: cytologic examination and carcinoembryonic antigen assay in fine needle aspirates.

OBJECTIVE

To compare the sensitivities of cytologic diagnosis by fine needle aspiration (FNA) with carcinoembryonic antigen (CEA) content of cystic brain tumors and to determine if CEA assay enhances the sensitivity of cytologic diagnosis and suggests a probable primary in carcinoma with an unknown primary source.

STUDY DESIGN

Thirteen consecutive aspirates were studied. Cytologic diagnosis was confirmed by histologic examination and follow-up. Fluid varied from 3 to 50 mL and from clear to bloody to mucinous. Cytologic examination was performed on Papanicolaou-stained smears. CEA was measured by enzyme immunoassay, with a cutoff of 5 ng/mL.

RESULTS

Benign: 3 (subdural hematoma, 2; arachnoid cyst, 1). Malignant: 10 (medulloblastoma, 1; glioblastoma multiforme, 4; metastatic adenocarcinoma with an unknown primary, 1; of breast, 1; oat cell, 3). Sensitivities: cytology, 50%; CEA, 50%; combined, 60%; specificity, 100%. High CEA (> 880 ng/mL) differentiated papillary adenocarcinoma of lung/gastrointestinal tract from renal and thyroid carcinoma. Mean CEA: oat cell, 216.7 ng/mL; adenocarcinoma, 0.5, > 880 ng/mL; glioblastoma and medulloblastoma, 1.6 ng/mL; benign, 0.6 ng/mL.

CONCLUSION

High CEA content enhanced the sensitivity of cytologic diagnosis of cystic metastases and favored a primary carcinoma of the lung or gastrointestinal tract.