Rationale: Cell block technique is a method which has many diagnostic values for body cavity. To increase the effectiveness, most laboratories have used two or more methods of diagnostics. Subjects and methods: A total of 39 patients with pleural effusion at the Respiratory Centre, Centre for Nuclear Medicine and Oncology of Bach Mai Hospital were studied from 1/3/2012 to 31/07/2012. Results and conclusions: The average age of the patients was 15.34 + or - 59.4 (age). Sex ratio (male/female) was 1/1. The colors of the fluidfrom malignant tumors were often pink or bloody (accountingfor 82.1 percent). There were several cancer types such as adenocarcinoma (94.8 percent), large cell carcinomas (2.6 percent), squamous cell carcinoma (2.6 percent). The cancer originating from lung occupied for 82 percent, ovary (7.7 percent), breast (2.6 percent), unknown (7.7 percent). The characteristics of adenocarcinoma on cell block were as follows: the size of cell nucleus was larger and the rate of nucleus/cytoplasm increased abnormally (100 percent), mitosis (48.6 percent), variation (37.8 percent), chromatin and prominent nucleus (91.9 percent)
cytoplasm with hallow tubes (positive PAS) (56.8 percent), glandular structures (91.9 percent), papillary (62.2 percent)
large area (35.1 percent), whole tumor cells separatedfrom each other (8.1 percent)
light shade around the tumor (81.8 percent)
sandy (5.4 percent).