Serous fluid cytopathology

This chapter is focused on the discussion and review of cytomorphology of benign and malignant lesions in the serous fluid, including pericardial and pleural effusions and peritoneal fluid (ascites). Infectious diseases, lymphomas, mesothelioma and other malignant lesions can be found in serous fluids. The most common malignant lesions are metastatic carcinomas, such as metastatic lung and breast carcinomas in pleural effusions, as well as metastatic gastrointestinal and/or gynecological carcinomas in peritoneal fluids. The diagnostic and differential diagnostic key features of benign and malignant lesions are listed and reviewed. In addition, the utility of immunohistochemical markers in the differential diagnosis is also discussed.