Intraoperative cytodiagnosis of metastatic brain tumors confused clinically with brain abscess. A report of three cases

BACKGROUND: Cystic lesions of the brain may have diverse etiologies, ranging from true cysts to malignant tumors with cystic degeneration. Preoperative determination of the exact nature of them as well as intraoperative diagnosis may be sometimes difficult or even impossible. Sensitivity and specificity of diagnosis will be improved by introducing new methods or combining traditional procedures. CASES: Three metastatic brain carcinomas with primary sites of breast, pancreas and prostate presented as cystic lesions and were confused clinically with abscess. Intraoperative frozen section was not revealing. Cytologic study of sediments of aspirated fluid uncovered malignant cells. CONCLUSION: When combined with frozen section, intraoperative cytologic studies in the form of crush preparation, fine needle aspiration or evaluation of aspirated fluid in cystic lesions (as in our cases) can improve diagnostic accuracy by detecting important diagnostic features that otherwise may be missed.