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What pathology is about |
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Contrary to common belief, pathologists do not work on murder victims.
On the contrary, nowadays pathology is of utmost importance in the
diagnosis of many diseases of the living. |
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What happens in a pathology practice or an institute of pathology? |
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In most cases, what is analyzed in pathology practices every day is far
to small to be gruesome. The most important doctor’s tool is the
microscope. When viewing tissue samples or individual cells, the
pathologist is able to see whether a patient suffers from cancer or any
other disease. |
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Where to the samples and specimens come from, that are analyzed in the pathology practice? |
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1| our team of drivers
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Surgical doctors, such as surgeons, gynaecologists, urologists,
dermatologists or otorhinolaryngologists remove morbidly altered organ
parts or even whole organs. In order to obtain a reliable diagnosis as
soon as possible, the tissue samples or organ resection specimens must
be processed the same day they were removed. A team of drivers (fig. 1)
picks up the samples, which are stored in special containers, every
afternoon and evening from the various practices and hospitals. |
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How can the samples be allocated reliably to a certain patient? |
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| 2| registration of the samples |
Upon arrival at the pathology practice in Vechta, the samples are
numbered so that they may be reliably identified and allocated (fig.
2). Following this, the patient’s details are recorded in the
computer-based practice information system and can be viewed from every
work place via the computer terminal. |
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Which processing steps are necessary before the pathologist can analyze the samples under the microscope? |
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3| cutting
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4| preparation
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At first, the tissue samples have to be cut down to size by the
pathologist to those areas which are relevant for the diagnosis, since
large tissue parts or organs can not be examined in toto (fig. 3).
The tissue thus gained is then placed into little plastic capsules and labelled with the id number (fig. 4). |
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5| dehydration
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A sophisticated processing technique is necessary in order to obtain
wafer-thin tissue sections. To begin with, the tissue samples have to
be dehydrated and perfused with paraffin. This is done by machines
(fig. 5). Depending on the size of the specimen, this process will take
between 3 to 12 hrs. This automated process normally takes place over
night. |
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6a| taking
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6b| embedding
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6c| covering
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The following morning, the samples are prepared further by
medical-laboratory assistants (MTAs). Their shift starts as early as 5
o’clock in the morning to ensure that diagnoses can be obtained as soon
as possible. The tissue samples pre-treated in the automates are taken
from their capsules (fig. 6a), put into small metal moulds (fig. 6b),
then covered with the capsule (fig. 6c), filled up to the rim with
liquid (heated) paraffin (fig. 6d), and finally placed on a cooling
device where they will be cooled down in the shape of a little block
(fig. 6e), that can then be removed from the mould (fig. 6f).
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6d| filling with paraffin
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6e| cooling down
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6f| taking of the block
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7| cutting
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8a| detail microtome
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These tissue samples within the paraffin blocks are then deep-frozen
(at about –10 to –15 degrees) and then further processed with a
special, extremely sharp slicing device (microtome) (fig. 7). Using the
microtome, wafer-thin sections are cut from these paraffin blocks,
about 4 – 5 micro meter in thickness, which is about 25 – 30 times as
thin as normal writing paper (fig. 8a).
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8b| stretching
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8c| mounting
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These wafer-thin samples are then stretched in a heated water bath (fig. 8b) and mounted on a glass slide (fig. 8c). |
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9| removing the paraffin
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Before the wafer-thin tissue on the glass slide can be further
processed, it has to be de-paraffined. This is done by the application
of warmth and by chemical processes (fig. 9). |
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10| staining
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After the paraffin has been removed, the samples are stained in
staining devices according to the diagnostic questions (fig. 10). In
pathology, we have several hundred histochemical stains, which can
stain various tissue and cell structures as well as anorganic
substances (such as iron, copper). In general, the pathologist uses
about 15 to 20 stains in his daily work. |
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11| covering
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12a| cleansing
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12b| allocating
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After having been stained in the staining device, the slides have to be
covered by wafer-thin cover plates. This will prevent possible wiping
off and is also done by machines (fig. 11). Finally, the finished
samples are cleansed by the medical assistants and allocated to the
respective cases (figs. 12a and 12b). |
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13| viewing under the microscope
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14| typing into the system
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The samples are then viewed by the pathologist (fig. 13). The
respective diagnoses are dictated on a data medium and then typed by
the secretaries in a pathology information system (fig. 14).
The written diagnoses are checked by the pathologist, then they are
printed and sent to the sending clinical colleagues. As a rule, it
takes about 20 hrs from the time the sample was taken to the finished
report with delivery to the sending doctor. If extra analyses are
necessary, however, this period may take longer. |
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15| storing the samples
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16| storing the results
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After the histological slides have been viewed, they are sorted into
special cupboards and stored there, so that even 3, 5, 8 or 10 years
later the samples are still available for comparing analyses (fig. 15).
The printed reports, too, are kept for at least 10 years in the
practice (fig. 16). |
