Information on the skin biopsy
Biopsy techniques
The Shave biopsy
Superficial tissue removal may also be performed
using a “Shave biopsy”, deploying a scalpel. The
scalpel is passed horizontally through a slightly-protruding
wheal, which is elicited by superficially spraying a local
anaesthetic. The flat excised tissue (“excidate”)
often rolls up as a result of the formalin-induced tissue-retraction,
which complicates subsequent handling. In order to avoid this
 rolling
up, one can lay the tissue out on a small piece
of filter paper, before it arrives at the fixing medium.(1,10)
Alternatively, one can place the excidate in the formalin-filled
container and then hold it at an oblique angle after 5 to
10 seconds, until the excidate floating in the fixing medium
sticks to the moist wall. If one then places the vessel upright
once more, the formalin will flow back and the piece of tissue
will remain hanging onto the wall, a procedure that can be
supported by pressing lightly with the flat side of the scalpel.
After the excidate has dried on the wall for about 60 seconds,
one shakes the formalin container: the excidate will then
come once more into the solution and will no longer roll itself
up.(9)
By using shave biopsies, exophytic tumours
in particular can be removed swiftly, with the bonus of obtaining
a preparation that can be assessed easily. On the other hand,
biopsies of changes taking place at skin level are technically
difficult with the scalpel. Even if one forms a skin-fold
with the finger, the inflexible blade of the scalpel frequently
results in relatively big blemishes. The risk of injury in
biopsies of this type is not negligible. In recent years,
razor-blades have consequently been recommended for deeper
shave biopsies: these are fixed at the sides and can be bent,
thus enabling a quite deep biopsy while sparing the surrounding
normal skin. In order to minimise the risk of injury to surgeons,
these flexible blades are fitted with a grip at the side.(11)
Even greater safety is provided by a procedure that is otherwise
identical
ring curettes
for once-only use, which are available in diameters
of 4 and 7 mm, and allow
precise,
sparing removal of superficial skin changes thanks
to their sharpness. (6)
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