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Discussion
and conclusion
The growth modalities
of Lobular Carcinoma are responsible for the diagnostic difficulties
which distinguish it. Its growth in aligned malign cells, in rows which
infiltrate the tissue but often spare the glandular structure (9) is
in fact typical. This type of structural conservation, which is often
associated with a poor connective tissue reaction (10), is responsible
for the limited opacity and the blurred contours which may accompany
its radiologic representation (1).
Furthermore, the neoplastic
cells may surround the ducts without obstructing or invading them, which
accounts for the rareness of microcalcification (1).
Finally, the growth
in multicentric foci and the affection of the contralateral mamma (11)
make the accuracy of the staging by means of traditional diagnostic
imaging even more difficult.
In such cases, the great
sensitivity of the RM test can prove particularly effective in recognising
with greater reliability neoplastic foci, in supplying a more precise
representation of them and therefore in establishing the actual extent
of the pathology.
The advantages for
the patients are evident, especially in the cases which provide for
conservative surgery. The options offered by the computerised methodology
are in fact the high contrast resolution power, which makes it easier
to distinguish the neoplastic tissue from the normal parenchyma, and
the spatial resolution power, which plays a non marginal role in the
identification of the smaller foci (beneath 2.5 mm), possibly also when
contralateral.
It is not rare for
cases of Lobular Carcinoma, also investigated with MR, to be mammographically
represented as a quite restricted lesion, whereas the MR test indicates
a much larger size.
MR breast investigation,
which enables both a morphological and functional documentation with
respect to the parenchyma, reproduces with the latter the modalities
of contrast uptake, thus supplying information with regards to the vascular
features of the tumour.
The scientific interest
of this aspect goes along with the accuracy of the diagnostic methodology.
The underlying aspect of RM imaging is the phenomenon of neoangiogenesis
(12-14), that particular pattern of anarchic vascularisation which distinguishes
the neoplastic tissue and which in actual facts leads to an earlier
and more intense gadolinium uptake (15-22) compared to the surrounding
undamaged parenchyma. In the same areas in which the mammography proves
suspect, the MR morphological recognition of contrast impregnation foci
precociously enhanced within the normal glandular tissue therefore justifies
the diagnostic suspicion of malignity.
Furthermore, the MR
equipment is provided with a software which quantifies the amount of
uptake in time, by producing a graph which shows as the abscissa the
time factor and as ordinate the signal intensity and therefore, indirectly,
the amount of gadolinium absorbed by the focus under examination. This
graph is designated as Intensity/Time Curve; it represents the functional
parameter of the investigation and it is typical of neoplastic foci,
in which the curve rises immediately and reaches high levels within
the first minute after the injection (Fig.
1).
What emerges from this
work is that, in the case of Lobular Carcinoma, this last dynamic parameter
has not always presented itself as such. Sometimes, in fact (in 67%
of cases) the rising of the curve has been preceded by an evident "delay"
(Fig. 2).
Taking into account
the histological and infiltrative features of this neoplastic histotype,
a biologic explanation of this delay in the uptake of gadolinium could
be found in the existence of a greater stromal scirrhous component in
certain Lobular Carcinomas which somehow slows down the afflux of the
contrast medium.
In these cases, the
vital neoplastic component, nourished by the angiogenesis, would only
appear at a later stage to produce the conventional pathologic curve.
The above considerations
appear to support the hypothesis according to which the MR methodology
may be considered a testing instrument for certain biologic parameters
inherent in the tumour itself, the most important being its vascularisation
and therefore its vitality.
Therefore, in conclusion,
while, on the one hand the diagnostic accuracy demonstrated by the methodology
might, on a routine basis, supply more detailed information in the diagnosis
and staging of a neoplastic histotype which has so far caused quite
a number of diagnostic difficulties, on the other hand the possibility
of producing a functional representation of the pathologic tissue, as
well as a morphological one, enables the documentation of new investigation
parameters. In fact, the study of neoplastic vascularisation represents
a valid diagnostic opportunity, in vivo and not invasise, to obtain
information regarding the vitality and aggressiveness of the pathology,
these latter elements being quite indicative in the prognostic valuation
and in the therapeutic monitoring of the tumorous pathology.
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