Investigations of Skin Lesions

Investigations of Skin Lesions

Shave Biopsy

A shave biopsy is a technique where the very surface layer of skin is 'shaved' off by using the blade of a scalpel. It does not get a very deep sample of tissue, and so may not be the right technique for some skin cancers that go deeper into the tissue. However, it is very useful for taking samples from large areas, where tumours are present in a few different sites or have borders that aren't very clear.

Some people say that a shave biopsy should be done with caution on pigmented (coloured) lesions. This is because if the lesion comes back as being a melanoma then the shave biopsy can cause some trouble with finding out further information about the lesion. While some people hold to this belief, others say that a shave biopsy can be a very useful tool in pigmented lesions.

A shave biopsy will consist of the following steps:

1.  Firstly, the area will have a small amount of local anaesthetic injected into it to numb it.

2.  The actual removal of the lesion can be done in a few different ways:

a.  Very sharp special scissors can be used to remove the lesion.

b.  A scalpel blade held along the surface of the skin can be used to remove the lesion.

c.  A razor blade can be slightly bent, with the sharp edge running underneath the lesion to remove it.

3.  If there is any bleeding, then diathermy (where an electrically charged piece of metal creates a very minor burn) or a substance called 'ferrous sulphate' can be used.

Generally, a shave biopsy will heal very well, with little bleeding and usually no scarring.

http://www.youtube.com/watch?v=nbdmmukko4s

Punch Biopsy

A punch biopsy is mostly used when a doctor is a little uncertain about what the lesion is. This usually means that there is a possibility that the lesion is a cancer of some sort, but the doctor is not one hundred percent certain and does not want to remove it without checking first.

A punch biopsy can be used, for example, to tell whether a mole is simply a mole or actually a melanoma. Usually the sample will be taken from the area that looks the most 'suspicious'.

Other indications for a punch biopsy include in the investigation of:

·  Skin cancers such as basal cell and squamous cell carcinomas of the skin;

·  Bullous skin disorders (where the layers of the skin surface break apart, and the 'gap' between them fills with fluid);

·  Inflammatory skin conditions; and

·  Odd looking lesions with an unknown cause.

The doctor will do the following during a punch biopsy:

1.  Firstly, they will clean the skin.

2.  Then they will inject the skin with a small amount of local anaesthetic to numb the area.

3.  After the anaesthetic has fully numbed the area, the doctor will gently hold the skin tight, so that it does not move.

4.  They will then take a small 'punch' with an object that looks like a pen with a small cylindrical blade at the end, and hold it vertically over the skin area.

5.  The doctor will then place the blade over the skin and rotate, creating a small circular cut.

6.  They will then remove the blade and pick up the piece of skin inside the cut with small forceps (surgical tweezers).

7.  The doctor will then cut the base from under the sample using a scalpel.

8.  The sample will then be placed in a fixative to be transported to a lab.

9.  The doctor will stop any bleeding by placing pressure on the site before applying a dressing, or putting in a single stitch to close the hole.

A punch biopsy is almost completely safe to do, and the only worry with doing one is that there will be damage to the tissues that lie underneath the biopsy site. These areas are places like the eyelid, the back of the hands in elderly patients, the fingers and the part of the cheek that is just under the eye.

A doctor will use their judgement to decide on where it is safe to do it, and in the vast majority of cases there is nothing to worry about.

http://www.youtube.com/watch?v=gd7j-wYwryY