Melanoma Diagnosis

A melanoma is often asymptomatic: that is, it does not produce noticeable symptoms. Most diagnoses of the skin cancer are made when patients notice an unusual mole or lesion and report it to their doctor. You should periodically check yourself for new moles, or moles that have grown or changed color or shape. A monthly self-examination (or even twice a month, if you’re at risk of developing skin cancer) lets you keep track of any changes to moles or other skin lesions. If a mole looks suspicious, your doctor will probably order a biopsy.

ABCDE Rule for Melanoma

A skin cancer self-examination is easy enough to perform. A full-length mirror, hand mirror or family member can help you check hard-to-see areas of your body. Memorize the ABCDE rule for skin cancer: check for Asymmetry, Border, Color, Diameter or Elevation changes.

Asymmetry: Does the mole have the same shape on one side as the other? If you were to divide the mole in half, would the two halves match? Odd-shaped moles should be reported to your doctor.

Border: A mole’s edges are usually smooth, and clearly defined when compared to the surrounded skin. “Scalloped” or “blotchy” borders may indicate a problem, as can pigment that appears to “bleed” into the surrounding skin.

Color: Moles are usually one color. A growth that is multi-colored, or changes in color tone, should be considered suspect.

Diameter: A sudden increase in mole size should be investigated, especially if the growth is larger then six millimeters across (about the area of a pencil eraser).

Elevation: If a previously flat mole suddenly becomes elevated (raised up from the surrounding area), report it to your doctor.

In addition to the ABCDE rule for skin cancer, report any moles that bleed, cause itching or pain, or ulcerate (destroy epidermal tissue, causing a pit-like sore). Remember, the earlier melanoma is caught, the better the chance that it can be cured.

Biopsies: Confirming the Diagnosis

No matter how suspicious a mole looks, only a biopsy can tell whether the growth is cancerous. If the mole is small enough, the doctor will attempt to remove the entire growth in a procedure known as an excisional biopsy. If the growth is large, only a sample of tissue will be removed. The biopsy sample is then examined for microscopic signs of cancer.

Once melanoma has been diagnosed, it must be staged. Skin cancer staging measures elements such as tumor thickness, involvement of lymph nodes, and whether the melanoma cells have affected other organs or not. The spread to other sites or organs is called metastasis.

TNM Staging for Skin Cancer

Skin cancer, like many other types of cancer, is most often staged according to the American Joint Committee on Cancer staging system. The AJCC system rates a tumor according to its TNM score:

  • T: The thickness of the tumor. A measurement of how deeply the tumor has penetrated into the skin. Also known as “Breslow thickness,” the depth is measured in millimeters.
  • N: The N score (“node status”) indicates whether the skin cancer has spread to the lymph nodes and, if so, how extensively.
  • M: Indicates whether metastasis has occurred, either to the internal organs or other areas of the skin.

A cancer graded by the TNM method will have a number assigned to each letter. The tumor may be referred to as “T1, N1, M0,” for example, indicating how far the cancer has spread.

The American Joint Committee on Cancer publishes cancer classification systems used by many medical organizations, including the American Cancer Society. The AJCC uses the TNM grading to classify melanoma by stages. The higher the stage, the more advanced the disease and the worse the prognosis. Melanoma’s stages are divided as follows:

Stage 0: The melanoma is present only in the epidermis- the top layer of the skin — and has not spread.

Stage IA (T1a, N0, M0): The melanoma is still localized and is less them 0.75 millimeters thick. The tumor has spread to the upper level of the dermis — the second layer of skin.

Stage IB (T1b-2a, N0, M0): The tumor is between 0.75 mm and 1.5 millimeters thick, and has penetrated further into the dermis.

Stage IIA (T2b-3a, N0, M0): The tumor is now between 1.5 to 4 millimeters in depth, and has reached the lower dermis.

Stage IIB (T3b-4a, N0, M0): At a thickness of more then four millimeters, the cancer has penetrated deeper than the dermis. The melanoma is, however, still localized.

Stage III (T4, any N, M0): Lymph nodes have been infiltrated with melanoma cells. This may occur at any thickness.

Stage IV (any T, any N, any M1): The cancer has spread to other organs, or other areas of the skin. Metastasis may occur at any thickness level, and with or without lymph node involvement. This stage offers the worst prognosis.

Clark Method

The Clark method is a slightly different method of staging for melanoma. Instead of measuring the total thickness of the tumor, Clark staging measures only how deeply the tumor has penetrated the skin. Generally, the AJCC staging system is preferred. If your doctor used the Clark methods, its levels have these approximate equivalents to AJCC scores:

Clark Level AJCC Stage
I 0

Other Prognostic Factors

In addition to TNM factors, the presence of tumor ulceration is important in prognosis. Tests may reveal high levels of lactate dehydrogenase (LDH) in the blood. LDH levels indicate possible tissue damage. Like ulceration, high LDH levels are a negative prognostic factor.


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McMasters, K., Swetter, S. (2003, April). Current management of melanoma: Benefits of surgical staging and adjuvant therapy. Journal of Surgical Oncology, 82(4), 209-216.