A rare type of skin cancer that can be life-threatening if it is not found in the early stages is called Merkel cell carcinoma (MCC). This cancer is often aggressive, which means it grows quickly and may spread to nearby tissues and organs. In most cases, it spreads to nearby lymph nodes, and it affects the outer layer of the skin (epidermis). The risk of developing MCC increases in people who have a weakened immune system, prolonged UV (ultraviolet) light exposure, and certain viral infections. While the primary treatment for MCC is surgery to remove the tumor, doctors may recommend additional cancer treatments to reduce the risk of recurrence. Furthermore, MCC is also known as Merkel cell cancer, neuroendocrine carcinoma of the skin, or trabecular cancer.
In general, it occurs very rarely and affects about 3,000 people in the U.S. each year. Moreover, the number of people who develop this type of skin cancer is steadily increasing, but it may be due to new diagnostic tests.
What Are Merkel Cells?
The cells are present deep in the epidermis (the top layer of the skin). Moreover, Merkel cells are a type of neuroendocrine cell that has both nervous and endocrine system functions. They are localized near nerve endings and provide a sense of touch. First time, these cells were described by the German physician Friedrich Merkel in the late 1800s.
Symptoms
In most cases, the tumors of this type of skin cancer appear on sun-exposed areas of skin. Moreover, some people may notice a shiny or pearly lump on the area of skin that is exposed to the sun for long periods. Commonly, lumps appear on the face, neck, arms, or eyelids. In more advanced cases, the lump can break open into a wound or sore, but it may also be:
- Firm
- Itchy
- Raised or dome-shaped
- Tender
- Similar to a pimple or insect bite
- Red, purple, or bluish-red
If you notice lumps on the skin that resemble the previous lump types, immediately contact your healthcare professional.
Causes and Risk Factors
In most cases, people develop skin cancers (including Merkel cell carcinoma) due to prolonged exposure to the sun or artificial light sources (such as tanning beds). UV light causes damage to the DNA of the skin. Normally, DNA contains instructions that tell cells when to grow, multiply, and die. In people with Merkel cell carcinoma, DNA gives the cells different instructions, which makes them grow and multiply uncontrollably. When these abnormal cells become too numerous, they form a mass called a tumor.
Furthermore, approximately 80% of people with MCC have the Merkel cell polyomavirus (MCP). However, most people who are infected with MPC do not develop MCC. Generally, this is a common childhood virus that does not cause any symptoms, and there is no way to detect it. Moreover, experts do not fully understand how this virus causes skin cancer in some people, but they think it occurs when the immune system is not able to suppress the virus.
In addition, this type of cancer can affect anyone, but some factors could increase your risk of developing it. Check some examples below:
- Personal history of severe sunburns or tanning bed use
- People with other types of skin cancer, including basal cell carcinoma, squamous cell carcinoma, melanoma, and others
- Phototherapy (also called light therapy), which is often used to treat psoriasis and other skin disorders
- Weakened immune system – The immune system can become weakened due to certain health conditions (such as HIV infection, cancer, and others) or medicines (including immunosuppressants).
What Are The Potential Complications of Merkel Cell Carcinoma?
Those who develop MCC may also experience some complications, especially if the cancer is found in late stages or if people do not get treatment. Check some examples below:
- Metastasis – This is one of the most serious complications of MCC. In this case, the cancer spreads to other parts of the body.
- Increased risk of recurrence – This type of cancer tends to return even after successful treatment.
- Lung problems – These include dyspnea (shortness of breath), chest pain, and others.
- Liver issues – For example, nausea, vomiting, abdominal (belly) pain, and yellowing of the skin and eyes (jaundice).
- Confusion
- Treatment complications – Usually, people may notice the following symptoms after starting the cancer treatment (especially chemotherapy). For example, hair loss, extreme tiredness (fatigue), increased risk of infections, and anemia (low red blood cell count).
The previous health problems are not all possible complications that may occur in people with MCC. In any case, you may try to talk with your doctor about measures to reduce the risk of experiencing them.
How to Prevent Merkel Cell Carcinoma?
The best way to prevent MCC is to get protection against UV light. Check below some tips that may help reduce the risk of this type of skin cancer:
- Regularly apply a broad-spectrum sunscreen with a sun protection factor (SPF) of 60, especially when outdoors. You should reapply SPF if you are swimming or sweating.
- Do not go outside between 10 a.m. and 4 p.m. because during this time the sun’s rays are the strongest.
- Avoid tanning beds or sunlamps
- Discuss with your doctor about measures to do skin self-examinations
- Wear protection when outdoors (especially in the middle of the day), such as sunglasses, long-sleeved clothes, and a wide-brimmed hat.
Diagnosis
Usually, this type of skin cancer is diagnosed by a dermatologist. However, the diagnosis begins with a full-body skin examination and tests to rule out other conditions that look similar to MCC. These include noncancerous (benign) cysts, folliculitis (infected hair follicles), styes, and others. Doctors may also perform a skin biopsy if they suspect this type of cancer. During this procedure, they will take a small sample of the affected skin for testing. Doctors often check for cancerous cells. However, they may also perform other tests. For example:
- PET (positron emission tomography) scans
- CT (computed tomography) scans
- Sentinel node biopsy or needle biopsy
Once you are diagnosed with MCC, doctors will perform additional imaging tests to determine the extent (stage) of the cancer. It often helps make the best treatment plan for you.
Treatment
The primary treatment for people with MCC is surgery to remove the tumor. Check below some types of surgery used to treat people with this type of skin cancer:
- Mohs surgery – During this procedure, surgeons will remove the tumor and skin layers. They often try to preserve as much healthy tissue as possible.
- Wide local excision – This treatment involves the removal of the tumor and some healthy tissue around it.
- Lymph node dissection – Doctors often recommend this surgery when the cancer spreads to the nearby lymph nodes.
Frequently, MCC returns even after successful surgery. That’s why doctors may recommend the following treatments to reduce the risk of recurrence. Examples include chemotherapy, radiation therapy, and/or immunotherapy.
Frequently Asked Questions
When should I call the doctors?
Usually, it is advised to see a doctor if you notice unexplained changes to your skin. Check some examples below:
- Scaly or crusty skin lesion
- Sores that do not heal
- Unusual lumps (especially those that cause itching or pain)
- New mole or changes to an existing one
What is the survival rate for Merkel cell carcinoma?
The survival rate is different among people with MCC. Generally, the 5-year survival rate for people with localized cancer is about 75% to 80%. However, if the cancer spreads to other parts of the body, the same survival rate decreases to about 27%.
What is mistaken for Merkel cell carcinoma?
There are some conditions that can be mistaken for Merkel cell carcinoma. For example, lipoma, dermatofibroma, fibroma, vascular lesions, or cysts. MCC may also be misdiagnosed with squamous cell carcinoma, malignant melanoma, small cell carcinoma of the skin, and other types of skin cancer. If you have any other questions, ask your healthcare provider.
