Diagnosis of Skin Cancer

Skin Self-Exam

The diagnosis of skin cancer often begins when a person notices a skin change during a simple self-exam. Many experts suggest a monthly self-exam, especially in individuals who have a previous history of skin cancer.

  • After a bath or shower, you should examine your skin in a bright room that has a full-length mirror. A hand-held mirror will help you see the front, back, and sides (including the underarms and backs of the legs and feet), as well as the skin between the buttocks, the genital area, soles of the feet, spaces between the toes, and the scalp (a blow dryer can help to move the hair away from the scalp for easier viewing).
  • Note the location, size, shape, number, and color of all familiar moles, birthmarks, scars, and blemishes.
  • Record any new or unusual changes in the skin -for example, a sore that doesn't heal, or a mole that has grown or changed color.
  • If such changes are seen, a physician should be consulted as soon as possible.

Physical Examination & Skin Cancer Diagnosis

According to the American Cancer Society, individuals who are between 20 and 40 years of age should undergo a complete cancer-focused check-up—with full skin exam—every 3 years; older adults (age 40 and older) should be examined yearly. Routine physical examination by a physician should include a close inspection of the skin. Such inspection is especially important for individuals who previously have been treated for skin cancer.

Medical History & Skin Cancer Diagnosis

If the physician suspects that a portion of the patient's skin is abnormal, he or she will begin by taking a medical history. The physician will ask about previous cancer(s) and/or diseases, family illnesses, and the history of the skin lesion in question; for example: When did the spot first appear on the skin? Has the spot changed in size, shape, or color? Has it been bleeding or scaling?

Biopsy & Skin Cancer Diagnosis

Next, the physician will perform a biopsy—the removal of tissue for examination under a microscope by a pathologist (specialist in diseased tissue) or dermatologist (skin specialist). The type of biopsy that is chosen depends upon many factors, such as the type of skin cancer that is suspected, the lesion's location, and its size. Since most biopsies leave a scar, the patient should speak with the physician ahead of time to find out what type of biopsy will be used and the type of scar that it will leave.

All skin biopsies are conducted using a local anesthetic. The anesthetic is applied via an injection, so the patient will feel only a small needle prick and a mild sensation of pressure and/or burning that lasts for less than a minute.

The following is a list of types of biopsies:

  • Shave Biopsy—This form of biopsy is performed by the physician "shaving" off the top layers of skin–the epidermis and upper dermis–with a surgical blade. Shave biopsy is used to diagnose and treat noncancerous moles and many other types of skin disorders. Shave biopsy is not suitable for cases of suspected melanoma, since the depth of a melanoma may not be measured accurately by this method.
  • Punch Biopsy—A tiny tool resembling a cookie cutter is used to perform a punch biopsy. The tool is twirled on the surface of the skin until it cuts through the all the layers of the skin–the epidermis, dermis and upper subcutis. The round section of tissue is then removed for examination.
  • Incisional and Excisional Biopsy—If only a tiny piece of the skin is removed for examination, the procedure is called an incisional biopsy. A surgical blade is used to cut through the full thickness of the skin, creating a wedge-or elliptical-shaped incision. After the tissue is removed for examination, the cut edges are sewn together. Incisional biopsy has, in large part, been replaced by needle biopsy, since the latter technique is less time-consuming, less scar-producing, and less prone to infection. If the skin abnormality is small and it is completely removed by biopsy, the procedure is called an excisional biopsy. Excisional biopsy usually is performed if melanoma is suspected.
  • Fine Needle Aspiration (FNA) Biopsy—This biopsy method uses a fine, hollow needle attached to a syringe. The needle is inserted into the suspicious area; next, it is pushed back and forth to free some cells, which are aspirated (drawn up) into the syringe and smeared on a glass slide for analysis. FNA typically is used to biopsy enlarged lymph nodes near the site of skin cancer (e.g., melanoma). In this way, the physician is able to rule out or confirm the metastasis (spread) of cancer to the lymphatic system.
  • Sometimes imaging techniques may be used to position the needle during biopsy. These include computed tomography (CT or CAT scan), a computer-assisted technique that produces cross-sectional images of the body, and ultrasound, which produces images with high-frequency sound waves) FNA seldom is used to diagnose tumors such as melanoma.

    If skin cancer is diagnosed, the physician will determine whether the tumor is local (affecting only the skin at one site) or metastatic (having spread to tissues/organs beyond the skin). A very large or long-standing cancer may call for the biopsy of nearby lymph nodes to determine the extent of tumor growth. In addition, the physician may order imaging studies (X-rays, CT scans, etc.) to define the limits of the tumor and to pinpoint any metastases.

  • Sentinel Node Biopsy—Sentinel node biopsy is a new technique that can help physicians determine whether a skin cancer such as melanoma has spread to surrounding lymph nodes. In brief, a small amount of blue dye or radioactive tracer is injected into the area around the cancer. After about 1 hour, the lymph nodes near the tumor are checked for visible dye or radioactivity - signals that the primary or "sentinel" node has been located. Then the sentinel node is removed and microscopically checked for cancer cells. If cancer cells are detected, all remaining local nodes will be removed; if cancer cells are not found, additional lymph node surgery is unnecessary.
  • Therapeutic Lymph Node Dissection—If the lymph nodes near a skin cancer feel hard or enlarged, the physician may biopsy a node for microscopic analysis (sentinel node or fine needle biopsy methods may be used). If cancer cells are found within the node, then all lymph nodes within the area of the skin cancer will be removed surgically. This procedure is known as therapeutic lymph node dissection. After the nodes are extracted, they all will be examined for malignant cells to determine the extent of cancer spread.

Basal Cell Carcinoma/Squamous Cell Carcinoma Diagnosis

The diagnosis of either basal cell carcinoma or squamous cell carcinoma is based on the pathologist's (diseased tissue specialist) interpretation of a biopsy sample. Incisional, excisional, or punch biopsy methods typically are used to obtain tissue samples if such cancers are suspected.

Publication Review By: the Editorial Staff at Healthcommunities.com

Published: 15 Aug 1999

Last Modified: 26 Feb 2015