Cytomorphologic analysis of wet fixed and air dried oral buccal smears rehydrated with normal saline: A comparative study

Abstract

Introduction: Cytology is useful in disease diagnosis. The science of cytopathology is currently well standardized with two major branches, exfoliative and aspiration biopsy. The limitations of cytological diagnosis, are shrinking day by day. Exfoliative cytology is the study of cells exfoliated from body cavities. These exfoliated cells, from oral buccal mucosa are analysed by making smears. Smears are immediately fixed in alcohol for a period of 20 minutes and then stained with Pap stain. H & E, and Pap stains, are generally regarded as the best stains for assessment of chromatin pattern in cytologic smears since they ensure maximum resemblance with the corresponding cells in tissue sections. Cytological smears are used nowadays for mass screening purposes in camps. Taking bottles of alcohol for fixing and ensuring to store them in tightly sealed copulin jars, with smears, may be difficult. Air-dried smears may be used to overcome such practical difficulties. Rehydration of these air-dried smears can be a good alternative to wet fixation. Methodology: 20 healthy subjects were randomly selected and 2 oral buccal smears were taken from the same subject. One was fixed by routine alcohol wet fixation, the other was air dried for 24 hours, then rehydrated with saline for 20 minutes and fixed with alcohol. The slides were assessed after labelling. The scoring criteria was based on processing, preservation, nuclear details, cytoplasmic details and background staining. Two observers, blinded to the method of fixation, scored the slides, to avoid any bias. Results: The air-dried smears rehydrated with saline were almost equal, or even superior, in few characteristics, to wet fixed smears. The ease of processing was equal in both, while the nuclear details and cytoplasmic details were superior in saline rehydrated smears. However, the background stain was slightly darker in saline rehydrated smears compared to wet fixed smears. A student paired t-test was also done (p=0.639).