Melanoma is known as malignant melanoma or cutaneous melanoma, an aggressive form of skin cancer. It arises from the cells that give skin its color, the pigment-producing cells present in the epidermis called melanocytes.

Melanomas can develop anywhere on the body. Because melanoma cells stem from pigment-producing cells, melanomas are most frequently brown or black in color. In rare instances, melanoma develops from pigmented cells that are not associated with the skin, such as the eye or other internal organs.

Melanoma is the most serious form of skin cancer because if left untreated, can spread to other areas of the body. Like other skin cancers, however, when found and treated early, patients with melanomas can live long healthy lives.

Although melanoma is much less common than both basal cell and squamous cell carcinomas of the skin, it is the fifth most frequently diagnosed cancer in both men and women in the United States. [1]

What are the risk factors for melanoma?

The risk factors for melanoma include the following:

• Sun exposure

Both long term ultraviolet light exposure from sunlight and/or tanning lamps and a history of blistering sunburns early in life

• Fair skin

Individuals with light-colored hair, red hair, and light-colored eyes

• Moles

Individuals with 50 or more moles

• History of skin cancer

Patients who have already been diagnosed with skin cancer, basal cell carcinoma, squamous cell carcinoma, or melanoma

• A family history of melanoma

Individuals with a first-degree relative, a parent, sibling, or child, who has been diagnosed with melanoma

• Weakened immune system

Patients with decreased immunity due to chemotherapy, organ transplant, infections such as HIV/AIDS, or certain cancers like lymphoma

The signs & symptoms of melanoma

Benign healthy moles are far more common than melanomas. But distinguishing between the two can be difficult. Any change in an existing mole or the development of a new pigmented or unusual-looking new mole may be the first signs of melanoma.

Unlike melanoma, a healthy mole is generally uniform in color, light brown, tan or black. It is usually smaller than the size of a pencil eraser and the borders of the mole are easily distinguished from the normal skin surrounding the mole. 

The ABCDE Guideline

An analytical method to help detect early melanoma is the ABCDE guideline. Some or all of these features are manifested in most melanomas:

• Asymmetry – one half of the growth does not look like the other half
• Border Irregularity- Edges of the mole are uneven or blurred
• Color Variability –uneven coloring or multiple shades of color, like brown, black, and red
• Diameter – Larger than 5 mm in size (the size of a pencil eraser)
• Evolving or Changing – any change in appearance (size, shape, or color) or if the growth bleeds or itches

Related Article by Dr. Frey:  
How Do I Know if I Have Skin Cancer?
Skin Tags: What Are They and What Can You Do About Them?

What are the different types of melanoma?

There are several different types of melanoma. The most common type is superficial spreading melanoma.

Superficial spreading melanoma

Superficial spreading melanoma constitutes about 70% of melanoma diagnosed in patients. This form of melanoma grows gradually on the skin’s surface before it begins to invade the deeper layers. 

Nodular melanoma

Nodular melanoma can grow more quickly than other melanoma types and begins to invade into the deeper layers of skin as they develop. They comprise about 15% of melanoma cases.

Lentigo maligna melanoma

Lentigo maligna melanoma is a less common form of melanoma found commonly on older individuals. This is a very slow-growing melanoma that occurs in sun-exposed areas primarily on the head and neck.

Acral-lentiginous melanoma

Acral-lentiginous melanoma is the rarest form of melanoma but is the most common form of melanoma in dark-skinned individuals. This tumor appears on the nail beds of the fingers and toes, on the palms of the hands, and on the soles of the feet.

Amelanotic melanoma variant

Although uncommon, any type of melanoma may present as amelanotic or lacking pigmentation. These melanomas appear skin-colored, pink, red, or white. For this reason, these tumors are often difficult to diagnose, as they can be clinically confused with other non-pigmented benign skin growths. This often leads to a delay in diagnosis.  

How do you stage malignant melanoma?

The staging system most often used for melanomas is based on the American Joint Committee on Cancer (AJCC) TNM system. [2] The TNM staging system is a very detailed system.

• T: The T refers to the size and extent of the primary tumor.

• N: Refers to the number of nearby lymph nodes where cancer is detected on pathologic exam.
• M: Whether the tumor has metastasized to spread to regional lymph nodes or to other organs or areas of the body.

Physicians and cancer registries often refer to a five-stage system that groups the TNM stages into a less-detailed staging system.

What is the prognosis of malignant melanoma?

The prognosis of melanoma patients depends on the stage of the disease at the time of initial presentation.

The stages of malignant melanoma

Stage O: 

This stage is also called in-situ or non-invasive melanoma. Stage 0 tumors are limited to the epidermis, the most superficial layer of skin. In addition, there is no lymph node involvement and the tumor has not spread to other areas of the body. The 5-year survival rate of stage 0 melanoma approaches 100%

Stage I:

In Stage I melanoma, the cancer has spread into the dermis, the second layer of skin. The lymph nodes are not involved and the tumor has not spread to distant organs. The 5-year survival rate is over 90%

Stage II:

In this stage, the tumor is at least 1.01 millimeters in thickness but has not spread to lymph nodes or to distant organs. 5-year survival rates are between 50%-80% depending on tumor thickness and the presence of ulceration.

Stage III:

Regardless of tumor depth, Stage III tumors have spread to nearby lymph nodes. The 5-year survival rates range from 40%-70% depending on the presence of tumor ulceration, and the extent of lymph node involvement

Stage IV:

Stage IV tumors have evidence of spread to distant lymph nodes or organs far from the original site of the tumor. The 5-year survival rate is < 20%

Note: There are more specific subdivisions within each stage.

What is the treatment for malignant melanoma?

The type of treatment for melanoma depends on the location, size, and stage of the cancer. It also depends on the patient’s health and, on patients’ personal preferences.

Thin Primary Melanoma

• Surgical wide local excision is the mainstay of treatment for early-stage melanomas. The melanoma, and underlying tissue, along with a margin of healthy skin, is removed in an elliptical fashion with a scalpel. The tissue is sent for pathological evaluation to confirm that the cancer is completely removed. The majority of thin melanomas can be removed under local anesthesia in a doctor’s office or outpatient facility using this technique. 

• Mohs Micrographic Surgery(MOHS). Melanomas in difficult locations are often treated with MOHS. It involves removing skin cancer tissue, layer-by-layer, examining each layer at the time of removal until no evidence of tumor exists.

Higher Risk Melanomas

Treatment options for patients with melanomas that have grown deeper into the skin or have spread beyond the original tumor site may include:

• Surgery. In addition to the surgical removal of the melanoma, local lymph nodes may be sampled to assess whether the melanoma has spread. The surgical removal of local lymph nodes to evaluate them for the presence or absence of cancer is a technique known as sentinel lymph node biopsy (SLNB), 
• Immunotherapy. Also known as biological therapy, these types of treatments involve specialized medical therapies that can boost the patients’ immune system. This helps the body fight cancer. These treatments are often used for patients with melanomas that have a high risk to reoccur or for metastatic disease. FDA approved immunotherapies include the following: 

• • • Nivolumab
    • Pembrolizumab
    • T-VEC
    • Ipilimumab
    • Interleukin-2
    • Interferon alpha 2-b
• Targeted Therapy. Certain patients with metastatic melanoma may benefit from targeted therapy. This treatment involves the use of drugs that “target” the abnormal cancer cells without harming the normal cells. The FDA has approved the following targeted therapies for melanoma patients with a specific gene mutation:

• • • Cobimetinib
    • Dabrafenib
    • Trametinib
    • Vermurafenib
• Chemotherapy. Chemotherapeutic drugs are given intravenously or by mouth in order to destroy cancer cells. However, chemotherapy has had limited success in treating melanoma. The FDA has approved Dacarbazine (DTIC) for the treatment of metastatic melanoma.
• Radiation. High-energy rays may be used to shrink melanoma tumors. It can also be used to treat areas of melanoma that have a high risk of reoccurrence after initial treatment. Although not a common treatment option, radiation therapy may ease symptoms in patients with metastatic disease to the brain or bones.
• Clinical Trials. Clinical trials are research studies that test new or experimental melanoma treatments. They are available throughout the country. The best option for patients with late-stage disease may be participating in a clinical trial.

Prevention

To reduce the risk of melanoma and other skin cancer types:

-Avoid midday sun exposure: Sunlight intensity is strongest between 10 AM and 4 PM. Therefore, you should schedule daily activities in the early morning or later in the afternoon when possible. And remember to do this even in the winter and on cloudy days.

-Seek shade: especially midday when the sun’s rays are most intense.

-Sunscreen: Liberally apply a broad-spectrum sunscreen with an SPF of 30 or higher on all exposed surfaces year-round. Be sure to reapply it often, especially after sweating or swimming.

-Avoid tanning lamps and tanning beds.

-Perform monthly self-exams: With the help of a hand-held mirror, examine the skin on all body parts. Look for new growths or changes in existing moles, freckles, or birthmarks.

The bottom line

To summarize, melanoma is an aggressive skin cancer but it is treatable – even curable – if caught early. As is true for all skin cancers, there are things you can do to reduce your risk of getting this cancer.

Find addition skin cancer prevention tips at the Skin Care Foundation.

References:

1.  Siegel R, Miller K, Jemal A. Cancer Statistics 2019, Ca Cancer J Clin, 2019 Jan 69(1):7-34. https://pubmed.ncbi.nlm.nih.gov/30620402/ 
2. Keung E, Gershenwald J. The eighth edition American Joint Committee on Cancer (AJCC) melanoma staging system: implications for melanoma treatment and care, Expert Review Anticancer Ther., Aug 2018 (18)8: 775-784 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7652033/