Diagnosis of Melanoma

Because most melanomas arise on areas of skin that can be easily examined, early detection and successful treatment often is possible. Most dermatologists can accurately diagnose melanoma in 80–90 percent of cases.

The clinical presentation (how the growth looks) and the patient's history of a new or changing growth raises suspicions of melanoma. In these cases, a biopsy (small sample of skin) is obtained for evaluation under a microscope by a dermatopathologist (i.e., an expert at examining and diagnosing diseases of the skin).

The American Academy of Dermatology (AAD) recommends the ABCDE method for evaluating the characteristics of skin lesions to detect melanoma. This method involves the following:

  • Asymmetry (Does one half of the lesion resemble the other half?)
  • Border (Is the border of the lesion irregular or poorly defined?)
  • Color (Does the color of the lesion vary from one area to another?)
  • Diameter (Is the lesion the size of a pencil eraser or larger?)
  • Evolving (Does the lesion look different than other lesions on the skin? Has it changed in color, shape, or size?)

Regular self-examinations, as well as periodic, thorough examinations by a dermatologist, may aid in early diagnosis. Many experts recommend a monthly self-exam, especially in high-risk patients (e.g., those who have a history of skin cancer). Skin self-exam involves the following:

  • Exam the skin in a bright room with a full-length mirror. A hand-held mirror may be used to help see the skin on the front, back, and sides of the body, including the underarms, the backs of the legs and feet, between the buttocks, the genital area, the soles of the feet, the spaces between the toes, and the scalp). A blow dryer can be used to move the hair away so that the scalp can be seen.
  • Note the location, size, shape, number, and color of all familiar moles, birthmarks, scars, and blemishes.
  • Report any new or unusual changes, such as a sore that does not heal or a mole that has grown or changed color, to a physician as soon as possible.

Epiluminescence microscopy (ELM) is a diagnostic test that can be used to help make a diagnosis. In this test, the doctor uses a hand-held device called a dermatoscope to examine the lesion. Certain diagnostic criteria are used to help determine if the lesion is benign or malignant.

Newer diagnostic procedures involve computer imaging, lasers, and other devices. In dermascopy, the dermatologist uses a hand-held device called a dermascope to visualize pigment in the skin. This test can be used to enhance features of skin lesions and diagnose melanoma.

In some cases, nearby lymph nodes are tested to determine if cancer cells have spread. In this procedure, called sentinel lymph node biopsy, dye is injected at the tumor site and eventually travels to the nearest lymph node and stains it. The lymph node is removed and examined under a microscope for melanoma cells to help determine the stage of the disease.

Sentinel lymph node biopsy to diagnose melanoma is still somewhat experimental. Some maintain that it helps to remove tumor cells before they have a chance to spread to more distant sites, and others claim that migrating tumor cells can bypass these lymph nodes and that the procedure is unnecessary. Lymph nodes also may increase the ability of the immune system to fight the cancer and removing them might reduce this ability.

Publication Review By: Stanley J. Swierzewski, III, M.D.

Published: 14 Aug 1999

Last Modified: 24 Aug 2015