Melanoma

Melanoma

• Overview
• Understanding Your Diagnosis
• Staging
• Genomic Testing
• Pathology
• Treatment
• Lymph Node Mapping
• Clinical Trials
• Side Effects
• Follow-Up Care
• Insights
• Life After Cancer
• Glossary
• Resources
• Survivors
• Back to Cancer Types

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Melanoma

Overview

Receiving a melanoma diagnosis can feel shocking and overwhelming. Take a deep breath and learn as much as possible about your diagnosis. Once you have digested the news that you have cancer, make a plan to move forward confidently. The medical professionals caring for you will be a valuable source of information and support. The more you know about the type of melanoma you have, the more empowered you are to make the best decisions for you.

The skin has multiple layers: the epidermis (outer layer), dermis (inner layer) and hypodermis (subcutaneous tissue). Melanoma typically develops in the epidermis (see Figure 1). The neck and face are common sites for melanoma of the skin.

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.

Melanoma has two main stages of growth. The first is known as the radial growth phase. This is when the melanoma grows horizontally across the skin and stays within the upper level of the skin (epidermis). At this growth 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 in the lower dermis and hypodermis. The 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.

To predict the risk of spreading, melanomas are classified as:

• Thin (less than 1 millimeter, or about the thickness of a credit card) 
• Intermediate (1 to 4 mm)
• Thick (more than 4 mm)

The eye is composed of several layers of tissues, including the iris, ciliary body and choroid (see Figure 2). Two types of melanoma can form in the eye. 

• Uveal melanoma affects the middle layer of the eye, developing in the choroid, iris or ciliary body. 
• Conjunctival melanoma develops in the conjunctiva, the clear tissue that covers the white part of the eye and inside the eyelids. Conjunctival melanoma is more rare than uveal melanoma.

In addition, some melanomas may be amelanotic, which lacks pigmentation (color), and desmoplastic, which contains certain cell types.

Mucosal melanoma is also rare. It 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.

Although melanoma can affect the eye and mucosal linings, this guide focuses specifically on cutaneous melanoma, its treatment, side effects and survivorship.

If possible, find a doctor who specializes in diagnosing and treating melanoma. Also consider seeking a second opinion as another specialist may be aware of different treatment strategies and clinical trials.