If your physician suspects skin cancer, they will take a biopsy of your skin to make a diagnosis. A biopsy is a procedure where a small portion of your skin is removed. Then, the tissue is sent for examination under a microscope by a pathologist.

For non-melanoma skin cancer, a biopsy may be the only test and treatment needed. However, if there are cancer cells beyond the spot’s margins, you may need additional treatment.

If a biopsy shows that you have high-risk or later-stage melanoma, you may need additional testing, such as:

  • Magnetic resonance imaging (MRI): This test uses magnetic fields instead of X-rays to create images of the inside of the body. An MRI can also help your doctor measure the size of the tumor.
  • Computed tomography (CT) scan: A CT scan takes X-rays of the body from different angles to create a three-dimensional image that shows tumors or abnormalities.
  • Positron emission tomography (PET) scan: During a PET scan, a small amount of a radioactive sugar substance is injected into the body. Cells that use the most energy, such as cancer cells, absorb more of this substance than other cells. Then, a scanner creates images of your organs and tissues.
  • Ultrasound exam: An ultrasound creates a picture of the body tissues using sound waves.
  • Sentinel lymph node biopsy: This procedure is used to determine if cancer has spread to the lymph nodes. A sentinel lymph node is the first place cancer cells are likely to spread. A person’s sentinel lymph node will depend on where the cancerous lesion was detected. During the procedure, a dye and radioactive substance are injected near the cancer site. The substance can show where the sentinel lymph node is located. The surgeon will then remove one or more of these lymph nodes. The lymph nodes will be sent to a pathologist to determine if they contain cancer cells. If the lymph nodes are cancer-free, no additional lymph node surgery is required. If the lymph nodes contain cancer cells, this means the cancer has spread and further treatment is needed.

Basal Cell Carcinoma and Squamous Cell Carcinoma Staging

Basal cell carcinoma and squamous cell carcinoma don’t typically spread elsewhere in the body. In rare cases, a lymph node may need to be removed to determine if cancer cells are present.

Melanoma Staging

Melanoma is staged as follows:

  • Stage 0: Also called melanoma in situ, this means melanoma cells are only detectable in the top layer of the skin. At this stage, the cancer is unlikely to spread to other areas in the body.
  • Stage I: The primary tumor is thin and only in the skin. Stage I may be diagnosed as Stage IA or IB, depending on how thick the lesion is and if ulceration (breaks in the skin) is detectable under a microscope.
  • Stage II: The melanoma has grown further into the dermis, the skin’s inner layer. At this stage, melanoma is more likely to spread. Stage II may be divided into subgroups A, B or C, depending on the melanoma’s thickness and if ulceration is present.
  • Stage III: The melanoma has spread locally, to a regional lymph node near the original lesion or to the skin on the way to another lymph node (called in-transit metastasis, microsatellite disease or satellite metastasis). Stage III may be divided into subgroups A, B, C or D depending on which lymph nodes are involved, whether ulcerations are detected and whether the primary tumor has satellite lesions.
  • Stage IV: At this stage, the melanoma has spread to distant parts of the body, such as the skin, soft tissue, lymph nodes, gastrointestinal tract, liver, brain, bones or lungs. It is divided into subcategories as follows:
    • M1a: The cancer has only spread to distant soft tissue or skin.
    • M1b: Melanoma has spread to a lung.
    • M1c: Cancer cells have spread to any location other than the central nervous system.
    • M1d: Cancer cells have spread to the central nervous system, including the brain, cerebrospinal fluid, spinal cord or lining of the spinal cord or brain

There is also recurrent melanoma, which returns after treatment.

Merkel Cell Cancer Staging

Merkel cell cancer is staged as follows:

  • Stage 0: Cancer cells are only present in the outer layer of the skin and have not spread.
  • Stage 1: The primary tumor is 2 centimeters or less in diameter. Cancer cells haven’t spread to the lymph nodes or other parts of the body.
  • Stage IIA: The primary tumor is larger than 2 centimeters. Cancer cells haven’t spread to the lymph nodes or other parts of the body.
  • Stage IIB: The tumor has spread to nearby bone, muscles or cartilage. Cancer cells haven’t spread to the lymph nodes or other parts of the body.
  • Stage III: Cancer cells are detected in the lymph nodes. The tumor may be of any size and may have spread to surrounding cartilage, connective tissue, muscle and bone.
    • Stage IIIA: Cancer cells have spread to nearby lymph nodes, but nowhere else in the body. Or, there is no longer a tumor, but cancer cells were found in a nearby lymph node.
    • Stage IIIB: The cancer cells have spread to a regional lymph node or to a place in the skin on the way to a lymph node (called in-transit metastasis).
  • Stage IV: The tumor has spread to distant parts of the body, such as the brain, liver, bones or lungs.

Kaposi Sarcoma 

Staging for AIDS-related Kaposi sarcoma (the most common form in the United States) is as follows:

  • T (tumor) status:
    • T0 (good risk): The tumor is only found in the skin or lymph nodes or in the palate of the roof of the mouth. The lesions in the mouth are flat, not raised.
    • T1 (poor risk): The Kaposi sarcoma lesions are widespread. There may also be extensive oral KS with raised lesions in the mouth, lesions in the organs (such as the liver, lungs or intestines), and swelling or ulceration caused by the tumor.
  • I (immune system) status:
    • Immune system status is determined by a CD4 count blood test, which measures helper T cells (a type of white blood cell).
      • I0 (good risk): CD4 cell count is 150 or more cells per cubic millimeter
      • I1 (poor risk): CD4 cell count is lower than 150 cells per cubic millimeter.
    • S (systemic illness) status:
      • S0 (good risk):
        • No systemic illness
        • No history of thrush (a fungal mouth infection) or opportunistic infections (infections that affect people with weakened immune systems).
        • No history of night sweats, unexplained fever or unexplained weight loss lasting more than two weeks.
        • Karnofsky performance status (KPS) of 70 or higher (meaning you’re able to care for yourself).
      • S1 (poor risk):
        • Systemic illness is present and one or more of the following is true:
          • KPS under 70.
          • History of thrush or opportunistic infections.
          • HIV-related illness is present, such as lymphoma or neurological disease.
          • One or more of the following symptoms: Unexplained weight loss, unexplained fever or night sweats.

Overall:

  • Good risk: T0 S0, T1 S0 or T0 S1
  • Poor risk: T1 S1

Skin or Cutaneous Lymphomas

Staging for mycosis fungoides and Sezary syndrome:

  • Stage 1A: Skin lesions are present, but there are no tumors. The lesions cover less than 10% of the skin’s surface. The lymph nodes aren’t enlarged, the number of Sezary cells in the blood is normal and cancer cells haven’t spread to other organs.
  • Stage 1B: Skin lesions are present, but there are no tumors. The lesions cover 10% or more of the skin’s surface. The lymph nodes aren’t enlarged, the number of Sezary cells in the blood is normal and cancer cells haven’t spread to other organs.
  • Stage IIA: Skin lesions are present, but there are no tumors. The lesions cover up to 80% of the skin. Lymph nodes are enlarged, but the cell pattern looks normal under a microscope. Cancer cells haven’t spread to other organs and the Sezary cell blood count is normal.
  • Stage IIB: One of the lesions is one centimeter in width or larger. The lymph nodes may be normal or enlarged, but the cell pattern looks normal under a microscope. Cancer cells haven’t spread to distant organs and the Sezary cell blood count is normal.
  • Stage IIIA: Skin lesions cover 80% or more of the skin’s surface. The lymph nodes may be normal or enlarged, but the cell pattern looks normal under a microscope. Cancer cells haven’t spread to distant organs and 5% or less of the blood’s lymphocytes are Sezary cells.
  • Stage IIIB: Skin lesions cover 80% or more of the skin’s surface. The lymph nodes may be normal or enlarged, but the cell pattern looks normal under a microscope. Cancer cells haven’t spread to distant organs and Sezary cell blood count is low.
  • Stage IVA1: Skin lesions are present on any amount of the skin’s surface. The lymph nodes may be normal or enlarged, but the cell pattern doesn’t look abnormal under a microscope. Cancer cells haven’t spread to distant organs. The Sezary cell blood count is high.
  • Stage IVA2: Skin lesions are present on any amount of the skin’s surface. The lymph nodes are enlarged and the cell pattern appears abnormal under a microscope. Cancer cells haven’t spread to distant organs. Sezary cells may or may not be present in the blood.
  • Stage IVB: Skin lesions are present on any amount of the skin’s surface. The lymph nodes may appear normal or abnormal. Sezary cells may or may not be present in the blood. Cancer cells have spread to distant organs, such as the spleen or liver.

While experts are still determining how helpful this system is, staging for other skin lymphomas is as follows:

T (tumor) categories:

  • T1: Only a single skin lesion is present.
    • T1a: The lesion is 5 centimeters or less in width.
    • T1b: The lesion is more than 5 centimeters in width.
  • T2: There are two or more skin lesions present. They may be on the same area of the body or in nearby regions.
    • T2a: All lesions could fit within a 15-centimeter circle.
    • T2b: All lesions could fit within a 15- to 30-centimeter circle.
    • T2c: All lesions could fit within a circle that’s larger than 30 centimeters.
  • T3: The skin lesions occur in body regions that aren’t near each other or that are in three different regions.
    • T3a: The skin lesions are present in two of these body regions.
    • T3b: The skin lesions are present in three or more body regions.

N (lymph nodes) category:

  • N0: No lymph nodes are affected.
  • N1: Lymphoma cells are found in the lymph nodes near the lymphoma.
  • N2: Lymphoma cells are detected in at least two sets of lymph nodes from different parts of the body or there are lymphoma cells present in lymph nodes that don’t drain areas near the lymphoma site.
  • N3: Lymphoma cells are present in the lymph nodes deep within the abdomen or chest.

M (metastasis) category:

  • M0: Lymphoma isn’t found outside of the lymph nodes or skin.
  • M1: Lymphoma cells have spread to other tissues or organs.