Pitfalls and Problems in Breast Pathology
Ian O. Ellis and Sarah Pinder
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Definitive pre-operative diagnosis of breast lesions avoids patient uncertainty and anxiety, in part
by obviating the need for frozen section assessment. It allows planning of operating lists and bed
occupancy. In some cases open biopsy is avoided and benign lesions can be safely left in situ. Both
fine needle aspiration cytology (FNAC) and core biopsy are simple and cheap techniques for the diagnosis
of breast lesions which can be performed in the outpatient setting and have a low complication rate.
Both modes of diagnosis have disadvantages; in particular FNAC requires highly skilled and trained
personnel in both aspiration and assessment; as early as 1933 it was recorded regarding
aspiration cytology that "until the pathologist has familiarized himself with the various pitfalls,
errors are certain to occur" . Errors in diagnosis of breast lesions by either technique, may lead to
over-treatment or delay in diagnosis. In the first part of this course we will cover some of the most
commonly encountered and serious potential pitfalls in pre-operative diagnosis of breast lesions.
Case 1 - Figure 1 - Breast FNA (air-dried, Giemsa). Woman aged 43. Symptomatic mass, imaging probably benign.
Case 2 - Figure 1 - Core biopsy. Woman aged 52. Screen-detected, indeterminate calcification.
Case 3 - Figure 1 - Core biopsy. Woman aged 50. Screen-detected, suspicious microcalcification.
Case 4 - Figure 1 - Core biopsy. Woman aged 49. Indeterminate mass lesion on screening mammography.
Almost any breast lesion may produce diagnostic difficulty and a degree of selectivity is therefore
necessary in a seminar such as this. This has been achieved by reference to two main sources: data on
consistency of diagnosis from External Quality Assessment schemes in the United Kingdom organised by the
National Co-ordinating Group for Breast Screening Pathology and in Europe organised by the European
Breast Screening Pathology Group;
an informed audit of cases sent for second opinion from
other departments. It is, perhaps, not surprising that both routes produce similar problem cases which
fit into a relatively restricted group of diagnostic categories which can be considered under the
headings shown in Table 1:
Table 1 - Main categories of lesion that lead to diagnostic pitfalls in breast
|Effects of previous therapy|
|Pathological prognostic factors|
In practice the pitfalls described below may be avoided or reduced by the application of sound
general histopathological principles. These include the application of strict diagnostic protocols and
in this respect there is good world-wide agreement for most lesions. Participants in the symposium are
referred to the standard breast pathology texts in the reference list, including UK and European breast
screening pathology guidelines.
It is interesting to note that many diagnostic
difficulties arise with those lesions where complete agreement on diagnostic criteria has not yet been
reached. The aim in this presentation is to emphasise practical points of distinction rather than to
provide a comprehensive description of each lesion.
One further general point is pertinent. Experience has shown that in many cases difficulty in
diagnosis is related to sub-optimal specimen preparation, mostly poor fixation or tissue processing. A
comparatively minor investment of time and effort in improving the technical aspects of the diagnostic
process will be rewarded by considerably better quality of preparations and a consequent decrease in
unnecessary problem cases.
Until relatively recently the main role of the diagnostic histopathologist lay in the establishment
of a diagnosis of breast cancer from excision biopsy or frozen section. Apart from the examination of
loco-regional lymph nodes for the presence or absence of metastases it was unusual for any other
prognostic information to be supplied, or indeed requested. The treatment of breast cancer was
standardised, predominantly surgical and there was little attempt to stratify patients for appropriate
therapy on an individual basis. However, as mentioned previously, in the last two decades the treatment
of breast cancer has undergone dramatic changes and a much wider range of both local and systemic
therapeutic options is now available. Early diagnosis, especially since the advent of mammographic
breast screening, is detecting tumours which are likely to have a favourable outcome and it has become
extremely important to assess prognosis for each patient before a therapeutic plan is agreed.
A considerable amount of useful prognostic information is available from the careful
histopathological examination of routine breast carcinoma specimens.  The following factors,
all relatively simple to assess, have been shown to provide clinically relevant prognostic information,
provided that careful attention is paid to diagnostic guidelines and protocols.