(iv) Lesion may not be fully accessible  (v) Cancers with ulceration, fungation will not yield malignant cells in the smears because of presence of necrotic debris ; (vi) Location and characteristics of the tumourmucosa of oral cavity exhibits varying degrees of keratinisation at different sites leading to varied exfoliation in oral cancers ; (vii) Improper fixation: Air drying the smear or using a wrong fixative may produce artefacts and alterations in the cellular morphology; (viii) Cytopreparation
: Staining and processing errors; (ix) Subjective errors by the inexperienced or careless cytopathologists.
High rates of FLUS diagnoses (for which the value of molecular testing is being marketed) can represent problems at many levels, including diagnostic expertise, the quality of the aspiration, and cytopreparation
. (126) A recent nationwide educational survey by the College of American Pathologists found a troubling approximately 40% of circulated FNA slides felt to represent FNs were miscategorized as either benign or malignant.