5.1 Briefly discuss the molecular and genetic principles underlying the criteria of dyskaryosis.
Surprising as it may seem, the molecular correlates of dyskaryosis are largely speculative. The main morphological changes seen in dyskaryosis involve the nucleus and include increases in nuclear size, deformities in nuclear shape, and changes in chromatin texture. These likely reflect changes in nucleic acid metabolism that occur during neoplastic transformation, which include mutations in the genes governing the structure of the nuclear matrix and nuclear membrane. Changes in this structure may have profound effects on nuclear shape chromatin organization.
5.2 Cervical cytology is an example of medical image perception. Explain the meaning of the word ‘perception’ in this context.
In the general sense, perception describes the way in which humans give meaning to sensory input, including environmental sights, sounds, tastes, etc. In medical image perception, of which cytology is just one example, perception is the process of detecting, identifying, classifying and interpreting the visual clues contained within a medical image. The clues are often subtle and their interpretation can be subjective, but cytologists can achieve high levels of diagnostic accuracy with the proper training and experience.
5.3 Explain why the reported grade of dyskaryosis for a cervical sample does not always correlate with the grade of CIN ultimately discovered in a subsequent cervical biopsy.
The reported grade of dyskaryosis is normally taken to indicate the minimum grade of CIN present. However, there are several factors that may confound the correlation between cytology and histology. The nature of the lesion and sampling error are among the most influential. Neoplastic lesions are variable in size and location and may be more or less accessible by the various sampling devices used for cytology and histology. The population of cells collected for cytological assessment will almost certainly not be morphologically identical to the cells in the tissue sample collected for histology. Another complicating factor is the known variation that exists between and among cytologists and their histologist colleagues in the interpretation of cell samples.
5.4 Give possible reasons for the lack of effectiveness of cervical screening in reducing the incidence of cervical glandular neoplasia.
Several factors militate against a reduction in adenocarcinoma rates through cervical screening. Lesions often arise deep in the endocervical canal and many are beyond the reach of conventional cervical sampling devices. The colposcopic appearance CGIN is ill-defined and many such lesions are located beyond the visible field of the colposcopist. The cytological features of CGIN are more difficult to recognize than squamous lesions and their histological detection may also be problematical.
5.5 Describe the circumstances in which a report of ‘borderline nuclear changes’ would be considered appropriate. Explain the importance of minimizing the use of this reporting category.
The term ‘borderline nuclear changes’ is used by cytologists to indicate doubt over the significance of minor morphological changes in the cells of cervical samples. The category may be used in situations where there is an overlap in the features of benign conditions (such as inflammation and atrophy) and neoplasia. This ‘grey area’ is an unfortunate outcome of an imperfect screening programme. The management of women with borderline abnormalities is problematical, particularly if the changes persist on repeated sampling. In many cases there is no underlying abnormality but high-grade disease and even invasive cancer is not unheard of. For this reason women with persistent borderline abnormalities must undergo colposcopy, but many of these will be found to have no cervical disease. Colposcopy is not only an expensive procedure it is also a known cause of anxiety in women. Cytologists must always be mindful of these facts and use the borderline reporting category judiciously.