Small cell and ‘pale’ dyskaryosis

Abstract

The correct diagnosis of the highest possible number of cervical smears showing severe dyskaryosis (high grade squamous intra-epithelial lesion) is of fundamental importance in the cervical screening programme, and it is apparent from three lines of evidence that some diagnosable cases of severe dyskaryosis are being missed.First, a review of the smears of 97 women subsequently developing invasive squamous cell carcinoma concludes 'that many cytoscreeners and cytopathologists are unable to recognize (or are unaware of the existence of) the small and hypochromatic types of dyskaryotic and malignant cells' 1 .Second, both authors are frequently asked to review cervical smears for medicolegal reasons. When cytological errors have occurred, they have usually been present in more than one smear from the patient and have involved errors of interpretation, rather than detection. Often large quantities of abnormal cellular material have been misinterpreted as a normal smear constituent. When the abnormal cells are squamous in type, severe dyskaryosis of either small or large non-keratinizing cells has almost invariably been missed. Although, given the normal processes of screening, these errors are usually made by the primary screener, this is not necessarily the case, and checkers and pathologists alike have made similar errors.Third, experience of examiners in the British Society for Clinical Cytology (BSCC) Certificate of Competence Examination has suggested that the importance of nuclear hyperchromasia as a feature of dyskaryosis has been over-emphasized, and that some candidates have a 'blind spot' for the recognition of small dyskaryotic cells.We conclude that there has been a failure of education and training at all levels in this subject, and that as a result, not everyone has been taught to recognize the complete spectrum of the appearance of squamous dyskaryosis.Discussion of these problems in the standard textbooks is variable. The great range of appearances of squamous dyskaryosis was beautifully illustrated by Hashime Murayama for George Papanicolaou in his Atlas in 1954 2 , but subsequent works have been less comprehensive. Koss 3 describes the problem of small dyskaryotic cells and warns that they may be misinterpreted as other, non-neoplastic small cell types, but hypochromatic or pale dyskaryosis is not specifically emphasized. Vooijs 4 relates increasing degrees of nuclear abnormality to increasing hyperchromasia, while Coleman and Evans 5 describe the

Morphologic analysis of false negative SurePath® slides using Focalpoint™ GS computer‐assisted cervical screening technology: An Australian experience

“…In conventional smears such cells have long been identified as a source of false negative cytology. 4,5 Individually, these cells may lack the full range of abnormal features, but variation in size, N/C ratio, nuclear size and shape, chromatin structure and chromasia suggest HSIL. 6 More recently, such pale or bland variants of HG squamous lesion cells have specifically been reported as potential sources of error in liquid based cytology (LBC) slides, including SP.…”

Why do we miss rare targets? Exploring the boundaries of the low prevalence effect

“…There are some searches, however, that combine low target prevalence with very high stakes. For example, medical screening tasks like mammography or cytopathology screening (‘Pap tests’) are critically important searches for targets that are only rarely present (typically under 1% of cases; Fenton et al, 2007; Gur et al, 2004; Smith & Turnbull, 1997). Similarly, in airport baggage screening, a serious threat in a bag is a highly unusual occurrence (Rubenstein, 2001).…”

Even in correctable search, some types of rare targets are frequently missed

“…In contrast, in some very important visual search tasks, target prevalence is low. In airport security (Rubenstein, 2001) and medical screening tasks (Jiang et al, 2007, Gur et al, 2004; Pisano et al, 2005; Smith & Turnbull, 1997), for example, the targets (weapons or possible tumors) are very rare. Our desire to find these targets is high, but our expectation that one will be found in a specific stimulus will be low.…”