Taking Biopsies of Melanoma

Taking a biopsy to diagnose a melanoma is a precise technique with many variables to consider in order to achieve the correct result. Some of the common issues involved with the biopsy of a worrisome mole are outlined here.

Where melanoma is suspected the recommended biopsy approach is complete excision with a 2mm margin. The first key consideration is whether the whole lesion can be removed by the biopsy. In order to provide the pathologist with the best material for making the diagnosis under the microscope, the whole lesion should ideally be removed. Sometimes when a mole is very large or in a cosmetically sensitive area such as the face, a small representative biopsy is taken. Whenever possible the person taking your biopsy will endeavour to remove the whole lesion.

There are three main ways a biopsy is taken. The formal excisional biopsy is the recommended technique in ideal situations. Other biopsy techniques are punch biopsy and shave biopsy.

An excisional biopsy with a 2mm margin to remove the whole lesion is performed by a scalpel incision. This provides the best specimen for the pathologist, the result being a linear scar with stitches. The direction of the biopsy scar should be along skin tension lines. This kind of biopsy technique may also be used just to take a representative sample of large lesions (an incisional biopsy).

A punch biopsy is a sharp circular tool of different diameters, which may be large enough to remove the whole lesion. This is a technique which is a convenient way to remove small spots. The hole left behind will be stitched back together to leave a very small linear scar.

Another technique is a shave biopsy. It heals with a graze and frequently an irregular pale circular scar. However a full excision biopsy is the recommended approach by the Australian and New Zealand Melanoma Guidelines.

It is important to remember that when the spot of concern is initially biopsied it is just a biopsy. While it is important to try to remove the whole lesion initially, this is just for the benefit of the pathologist to allow a more accurate diagnosis. When a spot is diagnosed as a melanoma it is almost always necessary to return to widely remove the area that was biopsied in order to ensure the melanoma has been all removed.

Following the biopsy the material must be carefully handled, again to facilitate the best result from the pathologist making the diagnosis. All biopsies must be carefully handled at extraction to avoid crushing of the specimen. This pinching of a biopsy can create a “crush artefact” which can severely limit the specimen’s interpretation in the lab.

Subsequently, punch and excisional biopsies can be placed directly into the formalin container. More care may be useful for shave biopsies. The shave biopsy provides a very slender piece of skin, which is prone to folding. This can hamper the assessment of the symmetry of the lesion and also whether it has been completely removed. A shave biopsy can be placed carefully on a firm card to provide support during fixation.

While there are many more facets to taking a biopsy of a worrisome mole, it remains critical that if there is a mole of concern this should be biopsied as soon as practically possible to prevent a delay in making the diagnosis of melanoma. Be reassured that your biopsy will be taken and processed only after careful consideration to achieving the best result.