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On the 28th
June, 2001, at St Bartholomew's Hospital, Dr Robin Moseley gave
an interesting, if not controversial, talk regarding the importance
of architecture in cervical ctyology and the potential loss of architecture
with the introduction of liquid based cytology.
Dr Moseley began
by highlighting two immunolgical markers MIB-1 and E-cadherin that
can be useful in distinguishing difficult areas e.g. differentiating
between a post-menopausal cervix and CIN 3.
The main features
of diagnosis can be split into two areas
- cytonuclear
features (abnormal chromatin)
- architectural
features (irregular structure)
These characteristics
vary depending on the differentiation of the tumour. With a well-differentiated
tumour architectural features are relied upon rather than cytonuclear
changes (chromatin appears normal, but can have malignant architecture),
whereas with a poorly differentiated squamous cell carcinoma,cytonuclear
features are relied upon.
Liquid-based
cytology and its implications!
Dr Moseley shared
his concerns over the eagerness to readily accept and introduce
this fairly new technique straight into the cervical screening programme.
This view was backed by his experience of the liquid-based preparations
and the noticeable loss of architectural features associated with
them.
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Conventional
Smear
|
LBC
Preparations
|
| Background |
Some features
of background remain |
| Cytonuclear
features |
Cytonuclear
features are the most important factor |
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Architectural
features:
- dispersed single cells
- cell aggregates
- cohort effect
- 3D characteristics
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Architectural
features:
- cell aggregates
- overall loss of architecture
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LBC claims to:
- reduce inadequates;
imporve preservation; improve representativeness (the preparation
is representative of the whole sample). However, LBC material
will eventually be thrown away also.
- increase
sensitivity in detection of CIN 3 (but small, single abnormal
nuclei may be difficult to identify and therefore are easily missed).
- facilitation
of HPV testing (HPV can also be carried out on conventional preparations)
- more rapid
screening (questionable, cells closer together may cause fatigue
on the eyes)
- facilitate
automation.
In conclusion,
he hoped (as do we all in the field of cytology) that the powers
that be will wait until they are confident with the LBC preparation
before rolling it out nationally and take into account the importance
of architecture and the potential implications of losing this diagnostic
feature.
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