Contaminants and Mimickers in Cytopathology

CONTEXT: Many contaminants are routinely encountered in cytopathology practice. However, because of lack of familiarity and experience with them, many are unnoticed, neglected, or confused with other structures of major relevance. AIMS: The purpose of this study was to intentionally introduce contaminants into the smears and to provide distinctive morphological criteria required for the microscopist to identify them confidently to avoid possible confusion. SETTINGS AND DESIGN: Prospective cross-sectional study. METHODS AND MATERIAL: This study included smears prepared from the buccal mucosa of healthy volunteers. Common contaminants were deliberately introduced into the smears, fixed using 90% ethanol, and stained with Hematoxylin and Eosin stain (H and E) and Papanicolaou stain (PAP). The study also included smears from leftover cerebrospinal fluid (CSF) and wet mount preparations. The morphology of these contaminants was studied and the results were tabulated. STATISTICAL ANALYSIS USED: Nil. RESULTS: The vivid morphological appearance of these commonly encountered contaminants were described and many of these mimicked structures of major relevance. CONCLUSIONS: Contaminants and mimickers can make the evaluation of cytologic specimens challenging and may necessitate secondary review by another pathologist or further workup. Knowledge and familiarity of these commonly encountered extraneous substances will help to prevent misinterpretation.