Written by: Aditi Kumari
Merkel cells sometimes referred as neuroendocrine cells are the cells found in the epidermis of the skin. They were discovered in late 1800s and are said to be touch cells and relay information like texture and pressure to the brain. Merkel cell carcinoma (carcinoma: cancer that originates in the skin or in tissue linings) arises from uncontrolled growth cells in the skin that share some characteristics from normal skin cells.
The risk of a person being diagnosed with MCC increases with certain factors like age, race, sunlight exposure, and immune function. It is believed that UV radiations play a significant role in the development of MCC.75 percent of the people diagnosed for MCC are over 65 years of age and it is more common in men than in women. While MCC is most commonly found on sun exposed areas of the skin it can also occur in a sun exposure protected area such as the scalp. MCC patients without a primary tumour (no original skin lesion (lesion: An area of abnormal tissue that may be either benign or malignant.) also do better, likely because their immune system was able to eliminate the primary tumour and thus are more likely to be able to fight small amounts of MCC elsewhere in the body as well.6 In contrast, patients on medications that reduce immune function are at higher risk of having their MCC recur.
The Merkel cell polyomavirus (MCPyV) was discovered by the University of Pittsburgh laboratory of Drs Patrick Moore & Yuan Chang and found to be frequently present in MCC tumors.7 The virus was found in 8 of 10 tumour tested, and was associated with the DNA of the tumour cells in such a way to suggest that it is involved in the development of MCC. The combination of a rapidly growing bump that may be red or purple yet is painless is a common scenario leading up to the discovery of a Merkel cell carcinoma. While a cyst can grow rapidly and is often red-purple, such an “inflamed cyst” will almost always be tender, which is very unusual for a Merkel cell carcinoma.
At the time of diagnosis, your medical team will perform other tests to “stage” your cancer. The stage is based on many factors including the size of the tumour, the results of a sentinel lymph node biopsy, and scans. The stage of the cancer is the single most important measure of the chance that the cancer will return.
Overview of MCC survival rates
Survival and disease recurrence are two critical measures of prognosis (how a patient will do after a cancer diagnosis). Recurrence refers to whether the cancer ever comes back (see the Recurrence page to learn more) and “MCC specific survival” refers to the likelihood of not dying from the cancer. The figures below show how MCC stage affects
survival after an MCC diagnosis. In general, patients with local or nodal disease have improved survival compared to patients with distant metastatic disease. Most deaths from MCC occur in the first three years after diagnosis.
Image Source: The Skin Cancer Foundation
References:
“Merkel Cell Carcinoma (MCC) > Fact Sheets.” Yale Medicine,
“Skin cancer types: Merkel cell carcinoma overview.” American Academy of Dermatology,
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