March 25, 2026
In 2025, approximately 104,960 new cases of melanoma are anticipated to occur in the United States, causing an estimated 8,430 deaths (1). The lifetime risk is approximately 3% for White people, 0.1% for Black people, and 0.5% for Hispanic people. Melanoma accounts for < 2% of total skin cancers diagnosed in the United States but causes most skin cancer deaths.
Melanomas occur mainly on the skin but can also develop on the mucosa of the oral, genital, and rectal regions and conjunctiva. Melanomas may also develop in the choroid layer of the eye, in the leptomeninges (pia or arachnoid mater), and in the nail beds.
Melanomas vary in size, shape, and color (usually pigmented) and in their propensity to invade and metastasize. Metastasis occurs via lymphatics and blood vessels. Local metastasis results in the formation of nearby satellite papules or nodules that may or may not be pigmented. Metastasis to skin or internal organs may occur, and, occasionally, metastatic nodules or enlarged lymph nodes are discovered before the primary lesion is identified.
There are 4 main types of melanoma and a few minor subtypes (1).
This type accounts for 70% of melanomas (2). Typically asymptomatic, it occurs most commonly on intermittently sun-exposed skin of young adults (eg, women’s legs and men’s torsos).
It often arises from a precursor nevus. The lesion is usually a flat plaque with irregular, raised, indurated, and tan or brown areas, which often have variegated pigmentation (red, white, black, and blue spots or small, sometimes protuberant blue-black nodules). Small notchlike indentations of the margins may be noted, along with enlargement or color change.
Histologically, atypical melanocytes characteristically invade the dermis and epidermis. This type of melanoma most commonly has activating mutations in the BRAF gene at V600.
Superficial Spreading Melanoma
Photo courtesy of Gregory L. Wells, MD.
This type accounts for 15% of melanomas (2). It tends to occur in older adults. It arises from lentigo maligna (Hutchinson freckle or malignant melanoma in situ—a frecklelike tan or brown macule).
Lentigo maligna usually occurs on the face or other areas of chronic sun exposure as an asymptomatic, flat, tan or brown, irregularly shaped macule or patch with darker brown or black spots scattered irregularly on its surface. In lentigo maligna, both normal and malignant melanocytes are confined to the epidermis.
When malignant melanocytes invade the dermis, the lesion is called lentigo maligna melanoma, and the cancer may metastasize.
This type of melanoma most commonly has mutations in the C-kit gene.
Lentigo Maligna Melanoma
CDC/ Carl Washington, M.D., Emory Univ. School of Medicine; Mona Saraiya, MD, MPH
This type accounts for approximately 5% of melanomas (2). It may occur anywhere on the body as a dark, protuberant papule or a plaque that varies from pearl to gray to black. Occasionally, a lesion contains little if any pigment or may look like a vascular tumor.
Unless it ulcerates, nodular melanoma is typically asymptomatic. Patients may present because the lesion enlarges rapidly.
This type accounts for only 1% of melanomas (2). Its incidence is similar across different skin pigmentations (3). However, people with dark skin infrequently develop melanoma overall. Thus, acral-lentiginous melanoma is the most common type among them.
Acral-lentiginous melanoma arises on palmar, plantar, and subungual skin and has a characteristic histologic picture similar to that of lentigo maligna melanoma.
This type of melanoma often has mutations in the C-kit gene.
Amelanotic melanoma is a rare type of melanoma that does not produce pigment. Any of the 4 main types can also be amelanotic. However, amelanotic melanoma is most often grouped with the minor categories of melanoma such as spitzoid melanoma, desmoplastic melanoma, neurotropic melanoma, and others.
Accounting for 2 to 8% of melanomas (2), amelanotic melanomas may be pink, red, or slightly light brown and may have well-defined borders. Their appearance may suggest benign lesions, or a form of nonmelanoma skin cancer, and thereby leads to delays in diagnosis and treatment, and possibly a worse prognosis.
Source: MSD Manuals. “Melanoma.”
By Vinod E. Nambudiri, MD, MBA, EdM, Harvard Medical School
Reviewed By Joseph F. Merola, MD, MMSc, UT Southwestern Medical Center
Available at: https://www.msdmanuals.com/professional/oncology/genitourinary-cancers/renal-cell-carcinoma
Copyright Notice: © 2026 Merck & Co., Inc., Rahway, NJ, USA and its affiliates. All rights reserved.
This content is an excerpt and has not been modified.
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