*Please note: This slide show represents a visual interpretation and is not intended to provide, nor substitute as, medical and/or clinical advice.
Melanoma is usually diagnosed by a dermatologist, a doctor who specializes in skin diseases.
Your doctor should carefully examine your skin - including the more private areas - to look for unusual changes.
Your doctor will assess the size, shape, color, and texture of all spots on your skin, especially any “ugly ducklings” that look different from their neighbors.
Your doctor may do a biopsy of any suspicious-looking mole. They will remove all or part of the mole and send it to a lab, where it will be looked at under a microscope.
In a punch biopsy, the doctor uses a pencil-like tool to remove a mole and the layers of skin directly underneath it.
In an excisional biopsy, the doctor uses a small knife called a scalpel to remove the mole and some of the normal skin around and below it.
After the biopsy, you will get a detailed report of its results. This is called a pathology report. Some of the things it will tell you are:
- Were cancer cells found? If so, what kind? And how far have they spread?
- How deep is the tumor at its thickest point? This is called the Breslow depth.
- How deeply has the tumor penetrated the skin? This is called the Clark level. This is not the tumor stage - we'll get to that in a minute. Doctors no longer use the Clark level to predict a patient's outlook, but it is still usually included in the pathology report.
- How close does the tumor come to the edge of the skin sample? This is called the margin.
- How many cells in the skin sample are actively dividing? This is called the mitotic count or mitotic rate. A higher number means that more cells are dividing.
- Is there ulceration? This is when there is a separation of the outer and inner layers of skin and may be associated with bleeding.
Lymph nodes are part of your immune system. Hundreds of them are located throughout your body, with many found in the neck, armpits, elbows, and groin.
Lymph nodes are small organs that contain and store large numbers of lymphocytes, white blood cells that help the body fight infection and diseases like cancer.
A lymph node biopsy is done to find out if melanoma has spread from the skin to nearby lymph nodes. All or part of a lymph node is removed and sent to a lab to be looked at under a microscope.
In a fine needle aspiration biopsy, the doctor uses a syringe with a thin, hollow needle to remove tiny pieces of a lymph node.
In a sentinel lymph node biopsy, the doctor injects blue dye into the area around the tumor. The lymph nodes that get stained with dye are the ones that melanoma is likely to spread to first. The dye-stained lymph nodes are removed and tested for cancer.
In an excisional lymph node biopsy, the doctor makes a small cut in the skin to remove an enlarged lymph node. The node is then tested for cancer.
Imaging tests may be done to look for cancer cells throughout the body.
- An MRI scan uses radio waves and magnets to create detailed pictures of areas inside the body.
- A CT scan uses a computer linked to an x-ray machine to make 3D pictures of areas inside the body.
- In a PET scan, you will be given an injection of a small amount of radioactive sugar. A special camera makes detailed pictures of the areas inside the body where the sugar collects. Cancer cells absorb much more of the sugar than normal cells do.
- An ultrasound scan uses sound waves to form pictures of tissues and organs on a computer screen.
Staging is a way of describing how much cancer is in the body and how far it has spread. Doctors do this using a system known as TNM, which can predict a patient's outlook.
- T is for tumor depth in the skin.
- N is for spread of the cancer to nearby lymph nodes.
- M is for metastasis, or spread of the cancer to distant skin or other organs.
Doctors combine the T, N, and M to get an overall cancer stage.
- Stage 0 melanoma is limited to the top layer of the skin. This is also known as melanoma in situ. The chance that it will spread is extremely low.
- Stage I melanoma is limited to the skin and is at most 2 mm deep.
- Stage II melanoma is limited to the skin and is more than 2 mm deep.
- Stage III melanoma may be any depth, and the cancer cells have spread to nearby skin or lymph nodes.
- Stage IV melanoma is metastatic. The tumor may be any depth, and the cancer cells have spread to distant lymph nodes or organs, such as the lungs, liver, brain, bones, and intestines.
- Melanoma Skin Cancer Stages. American Cancer Society. https://www.cancer.org/cancer/melanoma-skin-cancer/detection-diagnosis-staging/melanoma-skin-cancer-stages.html
- Melanoma: Stages. American Society of Clinical Oncology. https://www.cancer.net/cancer-types/melanoma/stages
- NCCN Guidelines for Patients. National Comprehensive Cancer Network. https://www.nccn.org/patients/guidelines/cancers.aspx
- NCI Dictionary of Cancer Terms. https://www.cancer.gov/publications/dictionaries/cancer-terms
- Tests for Melanoma Skin Cancer. American Cancer Society. https://www.cancer.org/cancer/melanoma-skin-cancer/detection-diagnosis-staging/how-diagnosed.html
- Urso C. Are growth phases exclusive to cutaneous melanoma? J Clin Pathol 2004 May;57(5):560.
Slide Show - Diagnosing Melanoma
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