Melanoma is one of the deadliest types of cancer. It is a type of skin cancer which develops in melanocytes, which are the cells of the skin that produce melanin (the pigment that gives skin its color). This type of skin cancer is often more severe than other types because it has the potential to metastasize, leading to advanced disease and even death. 

Skin cancer also happens to be the most common type of cancer. It accounts for over 76% of cancer deaths each year. The American Cancer Society estimates that in 2015, about 73,870 new cases of melanoma will be diagnosed in the United States. 

There are four types of melanoma:

1. Superficial spreading melanoma

Most common type of melanoma and accounts for about 70 percent of all cases. It usually starts as a previously benign mole.Most often seen in younger people. This type of melanoma grows along the outer layer of the skin, and gradually grows into deeper layers of the skin. It can be found anywhere on the body. It most often occurs on the trunk in men, the legs in women, and the upper back in both.

This type of melanoma initially appears as a flat or slightly raised discolored patch with irregular borders and is asymmetrical in shape. The color of the patch may vary betweenwhite, brown, red, tan, brown, black, or blue. 

2. Lentigo maligna

Similar to superficial spreading melanoma because it is found close to the outer layer of skin for quite some time before developing into deeper layers. It also usually appears as flat or slightly elevated, and is often brown, dark, brown, or tan in color. Elderly people who have a long history of sun-damaged skin are most affected. It is also most common in women and accounts for 4 percent to 10 percent of cases. Specifically, it most often occurs in light-skinned women’s faces who are older than 50 years old. It appears on the face as large, flat lesions. The risk of lentigo maligna spreading is lower than the other types of melanoma. 

3. Acral lentiginous melanoma

Also similar to superficial spreading melanoma because it spreads superficially before growing into deeper layers of the skin. However, this type also differs from the other types of melanoma in that is it most often found on the palms and soles of feet or underneath nail beds and because it usually appears as black or brown. For fair-skinned people, it accounts for 2 percent to 8 percent of all cases. For dark-skinned people, it accounts for up to 60 percent of melanomas. The cancerous patch of skin is also larger than others, with an average diameter of 3 centimeters. 

4. Nodular melanoma

Second most common type of melanoma. It accounts for about 15 percent to 30 percent of all cases. This type is more aggressive and usually develops faster than superficial melanomas. It is usually more invasive at the time it is initially diagnosed. It is known to be cancer once it becomes a bump that is usually black. Discoloration may also appear as tan, blue, red, skin-tone, brown, or gray. It is most often found in elderly people on the legs, arms, trunk, or scalp in men.