Diagnosing Melanoma: What Is an Excision Biopsy?

Melanoma is a skin cancer that occurs as a skin lesion. The appearance of the skin lesion or mole may prompt a possible diagnosis; however, to confirm that the mole is malignant, the dermatologist needs to perform an excision biopsy.

Suspicious Moles

The first thing you need to do to determine if the mole is suspicious or not is to apply the ABCDE method. If the mole is Asymmetric, has irregular Borders, has several Colors, is larger than 6 mm in Diameter and is Elevated and has evolved in the past few months or years, the mole is suspicious and needs to be tested.

In the initial stage, the moles may look harmless. If you suspect that a mole or skin lesion is malignant, you should test it. If the mole is itchy, bleeds or ulcerates, these may be warning signs.

Skin Biopsies

Blood tests for detection of melanomas don't exist, so a biopsy will be required. The excision biopsy, also known as a skin biopsy, is a simple test that will be performed under local anesthesia.

For large moles, the dermatologist will take a small part of the mole and will send the tissues for analysis, to determine whether it is benign or malignant. This procedure is also known as a small punch biopsy.

If the mole is not large and is not located on the face, eyelids or other areas that are difficult to operate on, an excision biopsy is possible and this will consist of the total removal of the skin lesion. The dermatologist will also remove 1 to 2 mm of skin tissue that surrounds the lesion. However, if the mole is larger, a small punch biopsy is recommended. Otherwise, the excision biopsy may be dangerous and cause a disruption of the lymphatic drainage in the mole’s area.

The skin punch biopsy should heal without leaving a scar, but the excision biopsy may cause scarring. The skin lesion, the subcutaneous tissue and the surrounding tissues will be analyzed by a histo-pathologyst.

Staging the Melanoma

If the skin lesion is malignant, the dermatologist will determine the stage of the cancer, so as to be able to find optimal treatment options. If detected in the early stages, the melanoma can be treated and the cancer may be stopped from spreading to other areas of the body.

The LDH test (lactate dehydrogenase) can determine if the melanoma is in metastasis. If the LDH levels are high, this means that the cancer has spread to the liver and other organs. Chest x-rays are also necessary to determine if the cancer has affected the lungs. The dermatologist may require a CT, MRI or PET scans, if need be.

If the dermatologist suspects that the cancer has spread to the lymph nodes, a lymph node biopsy may also be performed. If the biopsy reveals the presence of the S 100 protein marker, this means that the melanoma has affected the lymph nodes.

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