Merkel cells, found in the top layer of the skin, are touch receptors. They are found in high concentrations on the fingertips and lips but are also present in other areas of the skin. Merkel cell carcinoma (MCC) is when these cells multiple and grow out of control. It starts most often in areas of the body exposed to the sun.
This type of cancer is rare but the number of diagnoses have tripled over the past twenty years, with approximately 1,500 new cases each year in the United States. According to the Skin Cancer Foundation this is because in the 1990s a laboratory test was developed to differentiate this from other forms of cancer. Risk factors for Merkel cell carcinoma include being fair-skinned, over-exposure to the sun and immune suppression. It is most common in those over the age of 50.
A virus may also play a part in many cases of MCC. In 2008, scientists at the University of Pennsylvania discovered a virus that is present in about 80 percent of MCC tumors, although since 20 percent do not have the virus, it is not necessary to have the virus to develop MCC and it is not known if the virus causes the cancer. Between 60 and 70 percent of the population has been exposed to this virus, usually before the age of 20, although less than 1 in every 1000 people with the virus develop MCC.
Appearance of MCC Lesions
MC usually appears as a flesh colored, red or blue bump on the skin. It may resemble a blister or cyst but it grows quickly and the overlying skin breaks down. There is often a delay in diagnosis because it doesn't look like typical skin cancer lesions and you may think it is a red bump and only see a doctor when it doesn't go away or it begins to spread or grow.
Treatment of MCC consists of many of the same options as with other skin cancers:
- Excision of the lesion
- Biopsy and removal of lymph nodes, if affected
Depending on the stage of the disease as well as how well the patient tolerates treatment, all of these treatments can be used at the same time, however chemotherapy is not usually used unless the disease has reached stage IV or has returned after treatment.
As with all skin cancers, early detection and treatment is important. MCC can spread quickly and can be fatal. Early treatment, especially before lymph nodes are affected, greatly improve chances of survival.
"Frequently Asked Questions About Merkel Cell Carcinoma," Date Unknown, Staff Writer, Merkelcell.org
"Merkel Cell Carcinoma: An Uncommon But Often Lethal Skin Cancer," Date Unknown, Jayasri Iyer, M.D., Payl Nghiem M.D.,Ph.D., Skin Cancer Foundation