Lesser-Known Skin Cancers

While melanoma, basal cell carcinoma and squamous cell carcinoma account for 99% of all skin cancer cases, the following are other forms of skin cancer that are also important to be aware of.

Merkel Cell Carcinoma (MCC)

A rare, aggressive skin cancer that primarily occurs on sun-exposed skin such as the head and neck, as well as the arms, legs, and trunk. MCC usually appears as a firm, pink, red, or purple lump on the skin. Typically, these lumps are painless. Because MCC is a fast-growing cancer it can be hard to treat if it spreads to areas beyond the skin. Learn more about Merkel cell carcinoma from The American Cancer Society.

Kaposi Sarcoma (KS)

This type of cancer develops from the cells that line lymph or blood vessels. It can appear on the skin as a darkish/purple-colored tumor (or lesion) or on the inside of the mouth. Although lesions typically do not cause symptoms, they can spread to other parts of the body. KS is caused by the human herpesvirus-8 (HHV-8). Not everyone infected with HHV-8 will get KS. Typically, those most at risk are infected people whose immune systems have been weakened by disease or by drugs given after an organ transplant.

Types of Kaposi Sarcoma

There are a few different types of KS that are named from the populations that they are present in; however, the changes within the KS cells are all very similar. The different types of KS include:

  • Epidemic (AIDS-related) Kaposi sarcoma
  • Classic (Mediterranean) Kaposi sarcoma
  • Endemic (African) Kaposi sarcoma
  • Latrogenic (transplant-related) Kaposi sarcoma
  • Kaposi sarcoma in HIV negative men who have sex with men

Epidemic (AIDS-related) Kaposi sarcoma develops in those who are HIV infected. Human immunodeficiency virus (HIV) is the virus that causes AIDS. This type is the is the most common type of KS in the United States. Learn more about Kaposi sarcoma from The American Cancer Society.

Lymphoma of the Skin

Lymphoma is a cancer that starts in the lymphocytes--white blood cells that are vitally important in the functioning of the immune system. While lymphoma commonly involves the lymph nodes, it can begin in other lymphoid tissues such as the spleen, bone marrow, and the skin. The two main types of lymphomas are Hodgkin lymphoma and non-Hodgkin lymphoma. Lymphomas that originated only in the skin are called skin lymphoma (or cutaneous lymphoma).

In addition to some of the typical skin cancer treatments such as photodynamic therapies, chemotherapy, and targeted therapies, lymphoma of the skin may also be treated by stem cell transplants, immunotherapy treatments, and clinical trials involving lymphoma vaccines. Learn more about lymphoma of the skin from The American Cancer Society.