ABSTRACT
This study was conducted on 563 cases of body cavity effusions to establish the following points: 1. Determination of the underlying malignant causes 2. A search for the morphological feature of malignant cells for determination of their nature and site of origin 3. Differentiation between mesothelioma, cells and metastatic adenocarcinoma. Also, differentiation between non - Hosgkin's lymphoma and non- neoplastic lymphoid reaction.Qualitative cytoplasmic feature of prepared smears were studied by May- Grueniwald Giemsa [MGG] and nuclear feature in slides stained by Papanicolaou's stain [PAP]PAS stain and AB stain were used when needed 100 cells were assessed. Malignant effusions constituted 17.23% of all studied cases metaststic carcinoma was found to be the most common cause of pleural and peritoneal effusions.Adenocarcinomas formed the majority and the different primarysite of origin were breast, lung GIT and ovaries. Lymphoma/leukemia constituted the second frequent cause of body cavity effusions. It has been shown that MGG stain is highly valuable in differentiation of small cell lymphoma from lymphoid reaction. In small cell lymphoma all cells show monotonous nuclear staining, while in lymphoid reaction it is variable Methothelioma was the last frequent cause of malignant effusions. The most discriminating feature from reactive and highly reactive effusions are morula formation, cytoplasmic vacuolation, nuclear shape [irregular and oval] chromatin pattern [irregular and hyperchromatic], and prominent nucleoli. Metholelioma cells are PAS positive and negative after diastase digestion