Melanoma

Overview

Educate Yourself Immediately Upon Diagnosis

Hearing the words, “you have melanoma,” is overwhelming. But the more you know about your type of melanoma, the better prepared you will be to make treatment decisions with your medical team. New treatment options for all stages have developed at a rapid pace over the past few years, substantially improving outcomes. Today, several innovative immunotherapy and targeted therapy treatments

Melanoma, sometimes called malignant melanoma, is a cancer that starts in skin cells known as melanocytes, which produce melanin, the substance that colors the skin, hair and eyes. Damaged DNA can cause the melanocytes to grow abnormally. When melanocytes become malignant (cancerous), they become a melanoma.

Melanomas can develop anywhere on the skin, but they can also occur in the eyes and in mucosal linings, such as in the mouth, genitals and anal area. The neck and face are common sites for melanoma of the skin. Melanocytes may also form moles that can turn into melanoma.

Types of Melanoma

Although melanoma is the rarest of the skin cancers, it is considered the most serious type. It can easily spread into deep layers of skin as well as to lymph nodes and other organs. The skin’s layers include the epidermis (outer layer), dermis (inner layer) and hypodermis (subcutaneous tissue). Melanoma typically develops in the epidermis, which contains melanocytes (see Figure 1).

Cutaneous melanoma has four main types:

  • Superficial spreading melanoma, the most common type, usually develops from an existing mole.
  • Nodular melanoma usually appears suddenly as a bump on the skin.
  • Lentigo maligna melanoma typically begins on the face, ears, neck and arms that have been exposed to the sun for long periods of time.
  • Acral melanoma (ALM) is found on the palms of the hands, soles of the feet or under the nail bed.

Other subtypes include amelanotic, which lacks pigmentation (color), and desmoplastic, which is distinguished by the presence of certain cell types.

Ocular melanoma, a rare type of melanoma, develops in the eye. No screening tests are available for the disease, but routine eye exams help doctors find most ocular melanomas. Others may be found after they begin to cause symptoms or when the pupil is dilated during an eye exam.

The eye is composed of several layers of tissues, including the iris, ciliary body and choroid (see Figure 2). The iris, which is the colored area at the front of your eye, controls how much light enters the pupil. The ciliary body changes the shape of your lens when you focus on an object and makes the transparent liquid found between the outer layer of the eye and the iris. The choroid provides blood to the front part of the eye and to the retina, which is the light-sensitive ocular tissue at the back of the eye. Rarely, melanoma may also develop in the conjunctiva, the mucous membrane covering the eye, which keeps the eye lubricated.

Mucosal melanoma, which is also rare, develops in the mucosal lining of the body (a membrane that covers many body cavities and passageways). Because it often begins in concealed areas and causes no specific symptoms, many cases are diagnosed only after they have progressed to an advanced stage.

These areas in the body have moist mucosal linings:

  • The respiratory tract, in areas such as the sinuses, nasal passages and mouth. Head and neck mucosal melanoma is the most common type.
  • The gastrointestinal tract, including the anus and rectum (anorectal).
  • The female genital tract, including the vagina and vulva.

How Melanoma Grows and Spreads

Melanoma cells may enter the lymphatic system, a network of vessels that carry lymph (a colorless fluid) throughout the body. Once in this system, melanoma cells can spread to nearby lymph nodes and may also enter the bloodstream and travel to other parts of the body. Early treatment can stop melanoma before it spreads through the lymphatic system to lymph nodes in the region or to distant organs, which is why early detection and treatment are important.

In the first growth stage, known as the radial growth phase, the melanoma grows horizontally, staying within the upper layer of the skin (epidermis). During this phase, melanomas are not likely to metastasize (spread to other areas).

In the next phase, the vertical growth phase, the melanoma begins to grow down into deeper layers, such as the dermis and hypodermis, as well as up into the epidermis, and the risk for metastasis increases. This occurs because the lymphatic vessels are located in the lower dermis and hypodermis, and melanoma cells can use these vessels to spread to lymph nodes. Because of this, the thickness of a melanoma is the most important factor in determining the prognosis.

Melanomas are classified as thin (less than 1 millimeter, or about the thickness of a credit card), intermediate (1 to 4 mm) or thick (more than 4 mm).

Learn more about how certain types of melanoma are treated so you can make an informed treatment decision that is right for you.

 

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