Melanoma Diagnosis

Most melanomas are diagnosed using a skin biopsy.

The main types of skin biopsies are:

• Fine Needle Aspirate (FNA): technique in which a needle is inserted into the tissue or tumor to aspirate (take out) fluid and cells. This tissue/fluid is smeared onto a slide and is then looked at under a microscope. FNA can be performed in the office or under radiology guidance.
• Shave Biopsy: technique in which a portion of a lesion is cut off the surface of the skin using a scalpel in most cases. This is often performed by a dermatologist in the office.
• Punch Biopsy: technique in which a lesion is removed from the skin using a cookie cutter type device. This is used to remove small lesions or to sample a portion of a larger lesion.
• Incisional Biopsy: technique in which a lesion is removed from the skin by cutting out the affected area. This technique is often used to remove larger lesions.
• Excisional Biopsy: technique in which a lesion is removed from the skin by cutting out the affected area as well as a portion of normal skin surrounding the lesion. This technique is also used to remove larger lesions.

Following a biopsy, the tissue removed from the skin is examined under a microscope by a person specialized in analyzing skin specimens. This is often a dermatopathologist who is specially trained in examining bioposies for melanoma. After analyzing the tissue, the pathologist will issue a pathology report. If the lesion is determined to be a melanoma, specific information that is important in determining prognosis and recurrence risk will be reported in the pathology report.

The depth in millimeters and the presence or absence of ulceration provides the most important information related to prognosis at this time. Mitotic rate is also very important in determining a person’s prognosis. Following this initial biopsy, a wider local excision is often performed to ensure that the entire lesion was removed along with a clear margin of normal tissue around the melanoma.

A second step in the diagnosis of melanoma and to determine a person’s stage of melanoma is analyzing the lymph node status. When the original or primary melanoma has certain high risk characteristics, the lymph nodes are examined to determine if there is additional involvement. These characteristics include a depth greater than 1 mm, a Clark’s Level greater than IV, the presence of ulceration and sometimes regression. If the primary melanoma meets these characteristics, a sentinel lymph node biopsy is often performed

During a sentinel lymph node biopsy, a radioactive tracer and a dye are injected into the site of the primary melanoma. These agents are then traced to the “draining” lymph node basin. A small incision is made into the area where these two agents traveled and the lymph nodes involved are removed. They are then examined under a microscope to determine if there are any melanoma cells detected. In no melanoma cells are found, then no further surgical intervention is performed. If this lymph node does contain melanoma cells, then a second surgery to remove additional lymph nodes will be performed. These additional lymph nodes are also evaluated by a pathologist to determine if they contain any melanoma cells. This information is important in determining the stage of a person’s melanoma.

Common Pathology/Biopsy Terms and Definitions

• Cellular Description (the type of melanoma):
  • Superficial Spreading Melanoma
  • Nodular Melanoma
  • Acral Lentiginous
  • Lentigo Melanoma
  • Other: mucosal melanoma

• Breslow Thickness: depth a melanoma lesion extends below the skin surface, measured in millimeters
• Clark's Level: depth a melanoma lesion extends below the skin surface, based on involved skin layer (the larger the level number, the deeper into the tissue it extends
  • Clark's Level I - lesion involves the dermis
  • Clark's Level II - lesion involves the papillary dermis
  • Clark's Level III - lesion invades and fills the papillary dermis
  • Clark's Level IV - lesion invades reticular dermis
  • Clark's Level V - lesion invades sub-cutaneous tissue

  (Depending upon where the melanoma is located on the body, the millimeters of depth for each Clark level can vary widely, so one person's Clark's III may be 1 mm, while another person's is 2 mm.)

• Radial Growth Phase (RGP): The melanoma lesion is described as either having RGP present or absent. If present, RGP indicates that the melanoma is growing horizontally, or radially, within a single plane of skin layer.
• Vertical Growth Phase (VGP): The melanoma is described as either having VGP present or absent. If present, it is an indication that the melanoma is growing vertically, or deeper, into the tissues.
• Tumor-Infiltrating Lymphocytes (TILs): TILs describes the patient's immune response to the melanoma. When the pathologist examines the melanoma under the microscope, he/she looks for the number of lymphocytes within the lesion. This response, or TILs, is usually described as brisk, non-brisk, or absent, although occasionally can be described as mild or moderate. TILs indicate the immune system's ability to recognize the melanoma cells as abnormal.
• Ulceration: Ulceration is the sloughing of dead tissue. This can sometimes occur in the center of a melanoma lesion. The presence of ulceration may alter the stage classification of a melanoma. Ulceration is thought to reflect rapid tumor growth, leading to the death of cells in the center of the melanoma.
• Regression: Regression is described as being either present or absent. If it is present, the extent of regression is identified. Regression describes an area within the melanoma where there is absence of melanocytic growth. When regression is present, the total size of the melanoma is hard to characterize.
• Mitotic Rate: This term describes the frequency of division within the melanoma. Higher mitotic rates are associated with more rapidly dividing cells, and therefore larger lesions with greater potential for metastasis.
• Satellites: Satellite lesions are nodules of tumor/melanoma located more than 0.05 mm from the primary lesion. Satellites are described as being present or absent.
• Blood Vessel/Lymphatic Invasion: Blood vessel invasion, aka angioinvasion, as well as lymphatic invasion are described as being present or absent. If present, it means that the melanoma has invaded the blood or lymph system, respectively.

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