Overview of Rare Skin Cancers

Uncommon Types of Skin Cancer Don't Get the Attention They Deserve

Dermatologist examining woman's skin
Arthur Tilley/Stockbyte/Getty Images

Most experts now consider skin cancer to be an epidemic in the United States, with over 1.3 million new cases diagnosed each year and rising. The three most common typesbasal cell, squamous cell, and melanoma — account for the vast majority of skin cancer diagnoses, but there are several types of rare skin cancer that often don't get the attention they deserve. Here are five uncommon cancers that either arise from the skin or affect the skin indirectly:

Cutaneous T-cell Lymphoma

Cutaneous T-cell lymphoma (CTCL) is a group of cancers that arise from a type of white blood cell called a T-cell lymphocyte that becomes cancerous and affects the skin. In the United States, there are about 1,500 new cases of CTCL per year. Men are twice as likely as women to be affected, and most individuals are diagnosed after age 50.

In most types of CTCL (for example, mycosis fungoides, the most common type), the symptoms begin with the appearance of flat, red patches on the skin; in dark-skinned individuals, these may appear as either very light or very dark patches. The patches are very itchy, and may be dry and scaly. Some areas of skin may become raised and hard (called plaques). Later on, tumors may develop. Some skin folds become thickened and crack, leading to infection.

There is a wide variety of chemotherapy drugs, immunotherapy (for example, interferon), and targeted drugs (for example, denileukin diftitox or Ontak) now available to treat CTCL.

Merkel Cell Carcinoma

Merkel cell carcinoma (MCC) is a rare, aggressive type of skin cancer that forms on or just under the skin. Approximately 1,500 new cases of MCC are diagnosed in the United States each year. Most patients diagnosed with MCC are caucasian and over the age 50 (the average age is 69).

MCC lesions appear as firm, painless lumps within the skin. They are red, pink, or blue-violet in color, and are usually found on sun-exposed areas such as the head (especially around the eye and on the eyelid), neck, arms, and legs.

Treatment options include surgery, radiation therapy, and chemotherapy.

Kaposi Sarcoma

Kaposi sarcoma (KS) is a cancer that develops from the cells that line lymph or blood vessels. KS is caused by the Kaposi sarcoma herpesvirus (KSHV). The most common immune system problem that contributes to KS is infection with the human immunodeficiency virus (HIV), the virus that causes AIDS, but transplant recipients are another susceptible group.

The abnormal cells of KS form purple, red, or brown blotches or tumors on the skin. In some case, KS causes painful swelling, especially in the legs, groin area, or skin around the eyes. KS can cause serious problems, or even become life threatening when the lesions are in the lungs, liver, or digestive tract.

Treatment has significantly improved in recent decades and now includes highly active antiretroviral therapy (HAART) to treat AIDS patients with KS, as well as topical creams, surgical removal, cryotherapy (freezing with liquid nitrogen), and chemotherapy.

Sebaceous Gland Carcinoma

Sebaceous gland carcinoma (SGC) is a very rare, aggressive cancer originating in the oil glands in the skin. About 75% of cases are diagnosed around the eye, with the most common site being the upper eyelid, although it has also been found elsewhere on the head or neck, on the trunk, or in the genital area. Sebaceous cell carcinomas are most often found in women over 70 years of age. SGC is often slow growing and only spreads to other parts of the body in 1 out of every 5 cases.

Treatments available include surgery and radiation therapy.

Dermatofibrosarcoma Protuberans

Dermatofibrosarcoma protuberans (DFSP) is an uncommon type of tumor that begins as a hard nodule, grows slowly, and rarely spreads to other parts of the body.

It is caused by a genetic mutation that results in the overproduction of a molecule called platelet-derived growth factor. These tumors are usually found in the dermis (the inner layer of the two main layers of tissue that make up the skin) of the limbs or trunk of the body.

Treatment options include surgery, radiation therapy, and a newer drug called imatinib (Gleevec). However, DFSP is frequently misdiagnosed or treated incompletely, so be sure to find a dermatologist or other specialist with experience treating DFSP.

Catching Them Early

Regular skin self-exams are the best way to detect these rare skin cancers in their early, more treatable stages. If you see any new, changing, or otherwise unusual skin lesions, contact your doctor promptly.


American Cancer Society. (May 2016). What is Merkel Cell Carcinoma?

"Clinical Practice Guidelines in Oncology: Dermatofibrosarcoma Protuberans." v.1.2009. National Comprehensive Cancer Network. 1 May 2009.

"Mycosis Fungoides and the Sézary Syndrome Treatment." American Cancer Society. 1 May 2009.

"What is Kaposi sarcoma?" American Cancer Society. 1 May 2009.