The three most common forms of skin cancer are melanoma, basal cell carcinoma and squamous cell carcinoma. These account for the large majority of skin cancer diagnoses each year, however, there are some other, rare types of skin cancer.
The following is an overview of 8 rare forms of skin cancer
Merkel Cell Carcinoma - The Skin Cancer Foundation indicates that approximately 1,500 people are diagnosed with merkel cell carcinoma each year. Over-exposure to the sun and a suppressed immune system are the main causes, however scientists have also found a virus that is present in about 80 percent of those with this type of cancer. Lesions usually appear as a flesh, red or blue colored bump on the skin. Because it doesn't look like other types of skin cancer, diagnosis is often delayed until the skin around it begins to break down. Treatment usually includes excision and biopsy. Depending on the stage of cancer, radiation and chemotherapy may also be used.
Kaposi Sarcoma - Kaposi sarcoma is a cancer found in the tissue under the skin or in mucous membranes. Lesions appear as purple, red or brown spots on the skin. These tumors are usually benign but may need to be removed if they grown in size and number and block blood flow.
Dermatofibrosarcoma Protuberans - Dermatofibrosarcoma protuberans is an aggressive form of skin cancer that has a high recurrence rate although it does not normally spread to other areas of the body. It normally occurs within the deep layers of the skin on the torso. It begins as a small, firm patch of skin and can be flesh colored, red or purple. It progresses and grows very slowly. There is usually no discomfort or pain. When the cancer is detected early, Mohs surgery is usually the best treatment option. If the tumor has grown into or attached itself to muscle or bone, more aggressive treatments are used.
Keratoacanthoma - Keratoacanthoma is normally a benign growth that resembles squamous cell carcinoma. It usually appears on areas where there has been previous trauma or injury but can also occur from overexposure to the sun. It begins as a small round flesh or red colored bump and grows quickly for about 6 to 8 weeks. It remains stable for 1 to 2 months and then begins to disappear. Because it resembles squamous cell carcinoma, some doctors prefer to excise the lesion.
Sebaceous Carcinoma - This is a malignant cancer found in the sebaceous glands. These are small glands in the skin which produce an oily substance that helps moisturize the skin. Most of these cancers are found on the eyelids, face and neck although they can appear anywhere on the body where there are sebaceous glands. It appears as a reddish-yellow mass and when on the eyelid may be mistaken for a sty. It is a slow growing cancer. As with many forms of skin cancer, overexposure to the sun is a risk factor. Those with weakened immune systems are also at a higher risk of developing this type of cancer. Moh's surgery and excision are the most common treatments but radiation may be used if the cancer has spread.
Microcystic Adnexal Carcinoma - This is a rare, malignant cancer found in the sweat glands. It occurs most often in women between the ages of 50 and 70. It begins as a small tumor on the face or neck and may look like a small bump or raised patch of skin. It is usually local but can spread inward, invading bones, muscles, blood vessels, cartilage and nerves located behind the tumor. Overexposure to the sun or previous radiation treatments may contribute to the disease. Treatment consists of excision and sometimes radiation therapy.
Angiosarcoma - This type of cancer most often occurs in the lining of blood cells on the face and scalp. It may metastasize to other areas of the body including the lungs, lymph nodes, bone and liver. It can initially appear as a skin infection, bruise or lesion that has not healed. Because of this it is often not diagnosed until the cancer has spread. Treatment includes surgery to remove the tumor and chemotherapy and radiation if the cancer has spread.
Atypical Fibroxanthoma - This skin cancer usually appears on the face or neck of those who have had previous damage from sun exposure or radiation therapy. It usually begins as a small nodule and can grow to 2-3 cm. over a period of about 6 months. It usually appears as a single tumor. Moh's surgery and wide-area excision are recommended treatments.