Cancer is a disease in which cells grow in an abnormal way. Cells should grow in a controlled way to replace old or damaged cells. If the cells keep growing when new ones are not needed they form a tumor. Not all tumors are cancer, those that are cancer are called malignant. As the cancer grows, it can harm healthy tissue around it.
Melanoma is a type of skin cancer. It starts in the cells that give skin and moles their color. It is a less common type of skin cancer, but tends to be more dangerous. Melanoma is more likely to grow and spread.
Melanoma can start in any mole anywhere on the body such as the genitals, eyes, or under the nails. Most moles are harmless, but some can turn cancerous. Melanomas start at the the bottom layer of the epidermis. This allows them to quickly grow down into the dermis. There, the cancer can spread to the lymph nodes and blood vessels. The blood and lymph can carry the cancer to other areas of the body. Melanoma will often spread to the lungs, liver, brain, bones, and the intestines.
Types of Melanoma
Melanoma is grouped by where tumors start, how they grow, and how they look in a lab. Basic types are:
Superficial spreading—This is the most common type. Also the most common in young people. It grows on the top layers for a time before it gets deeper. It looks like a discolored patch. This type of melanoma can start in a mole that was harmless.
Nodular—Often noticed as a bump that is often black or has a sore. Tends to be more harmful.
Acral lentiginous—This is the most common type found in those of who are Black, Asian, or Hispanic. It may start as discoloration under fingernail or toenail, on palms of the hands, or soles of the feet.
Lentigo maligna—Often starts as flat or mildly raised discolored patch. More common in older adults in with a lot of sun exposure.
Melanoma. Merck Manual Professional Version website. Available at: https://www.merckmanuals.com/professional/dermatologic-disorders/cancers-of-the-skin/melanoma. Updated March 2019. Accessed May 9, 2019.
What is melanoma skin cancer? American Cancer Society website. Available at: https://www.cancer.org/cancer/melanoma-skin-cancer/about/what-is-melanoma.html. Updated May 20, 2016. Accessed May 9, 2019.
EBSCO Information Services is fully accredited by URAC. URAC is an independent, nonprofit health care accrediting organization dedicated to promoting health care quality through accreditation, certification and commendation.
This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.
To send comments or feedback to our Editorial Team regarding the content please email us at firstname.lastname@example.org. Our Health Library Support team will respond to your email request within 2 business days.