Serous Fluids

Abstract

Serous fluid can be aspirated easily and safely which makes cytological examination a perfect tool for the diagnosis of the underlying cause of any effusion. In general, malignant effusions can be diagnosed accurately and efficiently on cytology, and this often allows a firm management plan to be made without the need for more invasive tissue sampling techniques. Reactive effusions are common, and sometimes the cytological appearance points to the specific cause of the fluid accumulation. This chapter outlines the descriptions of the microscopic features of the various diagnoses underlying a serous effusion. In all cases, the clinical and radiological features need to be correlated with the cytological appearance as effusion cytology is a well-recognized trap for misdiagnosis. The reasons for this and helpful hints to avoid misdiagnosis are also provided in this chapter.