Understanding Your Melanoma Pathology Report

Posted on February 6th, 2009 by

If you’ve been diagnosed with malignant melanoma, the most serious form of skin cancer, your physician has made this diagnosis by removing (with a biopsy) the cancerous area on your skin and examining it under a microscope. Following this examination, you’ll receive a pathology report, which will describe your physician’s findings, including stage of disease and other important characteristics that will help determine your treatment plan. By clearly understanding these findings, you’ll be able to effectively participate in treatment decisions. Here are some of the terms you’ll likely see in your pathology report:
  • Your melanoma may be described as one of the following types:
  • Superficial Spreading Melanoma
  • Nodular Melanoma
  • Acral Lentiginous
  • Lentigo Melanoma
  • Other: mucosal melanoma
  • Staging:Stage of melanoma is determined by thickness, referred to specifically asBreslow thickness; this indicates the depth a melanoma lesion extends below the skin surface, measured in millimeters.  

In addition to thickness, staging of melanoma also includes status of local lymph nodes. Stages include:

  • Melanoma in Situ: Malignant melanoma cells are found only in the outer layer of skin cells (epidermis) and have not invaded to deeper layers.
  • Stage I:  Malignant melanoma is found in the outer layer of the skin (epidermis) and/or the upper part of the inner layer of skin (dermis), but has not spread to lymph nodes. The melanoma is smaller than 1 millimeter with or without ulceration (see definition below) or 1-2 millimeters without ulceration.  
  • Stage II:  The malignant melanoma is 1 to 2 millimeters with ulceration or larger than 2 millimeters with or without ulceration. Malignant melanoma has spread to the lower part of the inner layer of skin (dermis), but has not spread into the tissue below the dermis or into nearby lymph nodes.
  • Stage III:  The malignant melanoma can be any thickness with spread to regional lymph nodes.
  • Stage IV: The primary malignant melanoma is any size, but has spread to distant lymph nodes and/or distant sites.
  • Locally Recurrent Melanoma: Malignant melanoma has recurred, but is limited to skin and/or regional lymph nodes.
  • Recurrent and Refractory Stage IV Melanoma: Patients who have not responded to or progressed after initial systemic therapy (chemotherapy and/or biologic therapy) or have malignant melanoma that has recurred.
  • Clark’s Level: Unlike stage, the Clark’s level describes a primary melanoma tumor microscopically, dividing the skin into five levels and assigning the melanoma to a different level based on how deep the melanoma penetrated. Clark’s level indicates the depth that 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 dermisClark’s Level II—lesion involves the papillary dermis
  • Clark’s Level III—lesion invades and fills the papillary dermisClark’s Level IV—lesion invades reticular dermis
  • Clark’s Level V—lesion invades subcutaneous 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 describe 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 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 is described as being present or absent. If present, it means that the melanoma has invaded the blood or lymph system, respectively.
Additional Terms
  • The procedure used by your physician the remove the cancerous area on your skin is called a biopsy. Different types of biopsies include:
  • Shave Biopsy: a superficial area of the lesion is taken off, often with a razor-type blade.
  • Punch Biopsy: the removal of a circular area of skin with an instrument known as a punch, which comes in various sizes- sort of like a miniature round cookie cutter.
  • Incisional Biopsy: the removal of a portion of the affected tissue, for examination, using a knife.
  • Excisional Biopsy: the removal of the entire affected area and often some healthy tissue for examination using a knife.
  • If the term necrosis is used, it refers to the death of tissue and may also indicate the speed with which the tumor is growing.

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Tags: Melanoma

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