A comparative study of cell blocks versus cytospins and Conventional smears in effusions and cyst fluids cytology at Kenyatta National Hospital

Abstract

Excess fluids of the serous membranes are often the first clinical symptom of malignant tumors or of their metastatic manifestation. In one third of malignant effusions cytologygives the first indication of malignancy. Accurately diagnosing cells as being either malignant,benign 'reactive mesothelial cells' or adenocarcinoma in serous fluids is a common diagnostic challenge. To improve diagnostic accuracy, most laboratories use two or more preparation methods. Objective: The objective of this study is to compare cell block preparations versus cytospins and conventional smears in cytodiagnosis of effusions and cyst fluids. Design: This is a descriptive cross-sectional study. Subjects: Body fluids received in the KNH cytology laborotary that met the inclusion criteria forthe duration of the study. Setting: KNH Histology/Cytology laboratory. Methods: Fluid specimens received in the laboratory were centrifuged and two smears were prepared from exfoliated cells from the deposit. The remaining sample was divided into two equal volumes, one volume was processed using Shandon cytospin and the second volume was processed as a cell block. Ethical clearance was obtained from Kenyatta National Hospital/ University of Nairobi Ethics and Research Committee {KNH/UON-ERC) before carrying out the study. Consent to use the residual fluid samples was sought from the KNH Head of Department Laboratory Medicine through the cytology laboratory in charge. Analysis was done using SI'SS version 17.0 for Windows (SPSS Inc.). The test statistics for testing for the level of significance were McNemar test and Chi-square. Results In this study cell blocks had 16% samples with definite malignancy, cytospins had 18% and conventional smears 15%. In the suspicious category cell blocks had 6f%, cytospins 5%. conventional smears had 8%. Benign category had cell blocks with 64%, cytospins 65% and conventional smears had 69% while in the insufficient category the highest was in cell blocks with 13% followed by cytospins with 1 I% and conventional smears had only 7°/u. When the cell blocks were interpreted together with the cytospins and conventional smears the final cytodiagnosis was, malignant cases 19%, suspicious for malignancy 7''/0, benign 71% and insufficient were 2°1l1. Conclusion Cytospins are superior to both conventional smears and cell blocks in couccnuutiug cells. Cell blocks demonstrated the best architectural and cellular arrangement. Cell blocks when interpreted in association with cytospins and conventional smears increased the diagnostic accuracy in this study by 8.2%. Cytodiagnosis is shown to be dependent on cellularity, architectural and cellular arrangement and clinical information. Recommendations Cytospin method of processing body fluids should be adopted as a routine procedure. A minimum volume of 20 mls is recommended when multiple cytological techniques will be done for fluids. Cell blocks can be prepared in selected eases after review of the routine smears for better characterization of the tumor and where special stains and immunohistochemistry is required.