False negatives and false
positives in oral cytology
Makoto Suzuki 1,2) and Takashi Saku
1,2)
1) Surgical Pathology Laboratory, Niigata University
Dental Hospital
(Chief: Prof. Takashi Saku)
2) Department of Pathology, Niigata University School of
Dentistry
(Chief: Prof. Takashi Sake)
Summary: False negative and false positive oral cytology cases were
re-screened in order to determine the causes of the diagnostic
errors. False negatives were often based on insufficient
sample-taking, or inadequate smearing such as crowding of cells,
contamination by blood cells and drying of smears. Overlooking
atypical cells, underestimation of atypical cytomorphology and
mistaking carcinoma cells for normal mesenchymal cells were other
factors of false negative diagnoses.
False positives were mainly caused by
misinterpretation of cell morphology, such as overestimation of
cellular atypia, or mistaking the swollen non-epithelial cells for
carcinoma cells. In order to minimize false diagnoses, refined
technique of sample-taking and smearing, and improved ability in
cytodiagnosis are essential. When specimens are inadequate to
evaluate cytologically, because of poor preparation, diagnosis should
be suspended and re-examination or excisional biopsy is to be
indicated.
It seems to be rational to establish a
diagnostic system in which cytopathologists evaluate the quality of
specimens prior to cell diagnosis.
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