Early cytological diagnosis of diffuse malignant mesothelioma of the peritoneum: a case report.

Mesotheliomas are the most frequent primary malignant tumors of serosal cavities with a poor prognosis. A definitive and early diagnosis on effusion samples is important, because recent advances in therapy for patients with mesothelioma may result in an improved outcome if they are applied to stage I disease. We report a case of malignant peritoneal mesothelioma diagnosed repeatedly by cytology in ascites fluids 1.5 yr before the diagnosis was confirmed by biopsy histology. The cytological diagnoses were supported by immunocytochemistry, DNA-cytometry, and AgNOR-analysis. Routine cytology supported by three adjuvant methods enabled us to correctly establish the diagnosis. Our case suggests that a cytological diagnosis of malignant mesothelioma supported by adjuvant methods should not be rejected even if based on negative histological results.