Merkel Cell Skin Cancer
Merkel cell skin cancer (also known as neuroendocrine carcinoma of the skin or MCC) is a rare and aggressive form of skin cancer that usually appears as a flesh-colored or bluish-red nodule or bump on the skin. It typically develops on sun-exposed body areas, such as the head, neck, and arms, and can quickly grow and spread to other body parts.
Merkel cells are specialized cells in the skin that help with touch sensation. In most cases of Merkel cell skin cancer, the cancer cells are thought to arise from these Merkel cells.
Causes and Risk Factors
Merkel cells are found at the base of the outermost layer of skin. They are situated at nerve endings in the skin responsible for touch. The exact cause of Merkel cell skin cancer is not fully understood, but it is thought to be related to a combination of genetic and environmental factors. Some of the risk factors associated with an increased likelihood of developing Merkel cell skin cancer include –
- Exposure to UV radiation – Chronic exposure to UV radiation from the sun or tanning beds is a significant risk factor for developing Merkel cell skin cancer.
- Weakened immune system – People with weakened immune systems, such as those with HIV/AIDS, organ transplant recipients, or individuals taking immunosuppressive drugs, are at an increased risk of developing Merkel cell skin cancer.
- Age – The risk of developing Merkel cell skin cancer increases with age, with most cases occurring in people over the age of 50.
Merkel Cell Skin Cancer
4. Fair skin – People with fair skin are at a higher risk of developing skin cancer in general, including Merkel cell skin cancer.
5. History of skin cancer – People who have previously had skin cancer, including basal cell carcinoma and squamous cell carcinoma, are at a higher risk of developing Merkel cell skin cancer.
6. Exposure to certain chemicals – Exposure to certain chemicals, such as arsenic and pesticides, may increase the risk of developing Merkel cell skin cancer.
Having one or more of these risk factors does not necessarily mean an individual will develop Merkel cell skin cancer. Additionally, there may be other factors that contribute to the development of this cancer that are not yet fully understood by doctors.
Merkel cell skin cancer can appear as a flesh-colored or bluish-red bump or nodule on the skin, often with a shiny or smooth surface. The lesion may grow quickly and can be painless. Eight in ten people with Merkel cell carcinoma disease are likely to develop Merkel cell polyomavirus. Some other symptoms of Merkel cell skin cancer may include –
- A firm, painless lump on the skin that is increasing in size.
- The lump may appear red or purple.
- The surface of the lesion may be smooth, shiny, or waxy.
- The lesion may be tender or painful to the touch.
- The lump may be accompanied by swollen lymph nodes.
- The lesion may ulcerate and start to bleed or crust over.
- A rapidly growing lump appears in a sun-exposed area of the skin.
Not all skin lumps or bumps are cancerous, and some may be benign skin growths. However, any new or unusual growth on the skin that does not heal or that is changing in appearance should be evaluated by a healthcare professional. Early detection and treatment are important for improving the chances of a favorable outcome.
Diagnosis and Tests
If a healthcare provider suspects Merkel cell skin cancer, they will typically conduct a physical examination and take a biopsy of the suspicious lesion. During a biopsy, a small piece of tissue from the lesion is removed and sent to a laboratory for analysis.
In addition to a biopsy, other tests that may be used to diagnose Merkel cell skin cancer include –
1. Imaging tests – Imaging tests such as a CT scan, MRI, or PET scan may be ordered to determine the extent of cancer and whether it has spread to other parts of the body.
2. Lymph node biopsy – Merkel cell skin cancer can spread to nearby lymph nodes, which are part of the body’s immune system. If there is concern that cancer has spread to the lymph nodes, a lymph node biopsy may be recommended.
There are different types of lymph node biopsies, including –
Sentinel lymph node biopsy – A sentinel lymph node biopsy involves injecting a dye near the tumor to identify the first lymph node that is likely to contain cancer cells. The identified lymph node is then removed and examined for the presence of cancer cells. This procedure may be done under local or general anesthesia.
Fine needle aspiration biopsy – During a fine needle aspiration biopsy, a thin needle is inserted into the lymph node, and a sample of cells is removed and examined under a microscope for the presence of cancer cells. This is a less invasive procedure than a surgical lymph node biopsy.
Surgical lymph node biopsy – During a surgical lymph node biopsy, one or more lymph nodes are removed through a small incision in the skin. This is a more invasive procedure that is typically done under general anesthesia.
3. Skin biopsy – A skin biopsy is typically the most reliable way to diagnose Merkel cell skin cancer. During a skin biopsy, a healthcare provider will remove a small piece of tissue from the suspicious lesion, which will then be sent to a laboratory for analysis.
There are several different types of skin biopsies that may be used to diagnose Merkel cell skin cancer, including –
Punch biopsy – During a punch biopsy, a circular tool is used to remove a small piece of tissue from the lesion. The biopsy site may be numbed with a local anesthetic beforehand.
Incisional biopsy – An incisional biopsy involves removing a small piece of tissue from the lesion using a scalpel or other cutting tool. This type of biopsy may be used for larger lesions.
Excisional biopsy – An excisional biopsy involves removing the entire lesion, along with a small amount of surrounding healthy tissue. This type of biopsy may be used for smaller lesions.
If Merkel cell skin cancer is diagnosed, further tests may be performed to determine the stage of cancer, which helps to guide treatment decisions. The stage of the cancer is based on factors such as the size of the tumor, whether it has spread to nearby lymph nodes or other parts of the body, and the overall health of the patient.
Merkel cell carcinoma (MCC) is staged according to the American Joint Committee on Cancer (AJCC) TNM system, which takes into account the size and location of the tumor, whether it has spread to nearby lymph nodes, and whether it has metastasized (spread) to other parts of the body. The stages of Merkel cell cancer are as follows –
Stage I: The tumor is localized to the skin and is 2 centimeters or smaller in diameter. It has not spread to nearby lymph nodes or other parts of the body.
Stage II: The tumor is larger than 2 centimeters in diameter or has spread to nearby lymph nodes, but has not metastasized to other parts of the body.
Stage III: The tumor has spread to nearby lymph nodes and may be larger than 2 centimeters in diameter, but has not metastasized to other parts of the body.
Stage IV: The tumor has spread beyond the skin and nearby lymph nodes to other parts of the body, such as the lungs, liver, or bones.
Treatment options for Merkel cells depend on the cancer stages. Early-stage Merkel Cell Carcinoma is better than late-stage Merkel cell carcinoma. The surgical options for the removal of Merkel cell cancer include –
- Mohs Surgery – Removal of tumor and skin layers and preservation of healthy tissue as possible.
- Wide local excision – Removal of tumor and surrounding healthy tissue.
- Lymph node dissection – Surgical removal of lymph nodes especially metastatic cells.
Other Treatments for Merkel cell carcinoma typically involve a combination of surgery, radiation therapy, and/or chemotherapy. Immunotherapy may also be used in some cases.
- Chemotherapy – Chemotherapy involves using drugs to kill cancer cells. Chemotherapy may be used in combination with surgery and/or radiation therapy for advanced or metastatic Merkel cell carcinoma.
- Immunotherapy – Immunotherapy works by stimulating the body’s immune system to recognize and attack cancer cells. A type of immunotherapy called checkpoint inhibitors has been shown to be effective in treating Merkel cell carcinoma that has spread to other parts of the body.
- Radiation therapy – Radiation therapy uses high-energy X-rays or other types of radiation to kill cancer cells. Radiation therapy may be used after surgery to destroy any remaining cancer cells, or it may be used as the primary treatment for tumors that cannot be removed with surgery.
The specific treatment plan for Merkel cell carcinoma will depend on the stage of the cancer, the location and size of the tumor, and the patient’s overall health and preferences. Treatment decisions should be made in consultation with a healthcare provider who specializes in treating skin cancer.
The outlook for Merkel cell skin cancer depends on the stage of cancer at diagnosis and the treatment options available. Early detection and treatment are important for improving the chances of a good outcome.
According to the American Cancer Society, the 5-year survival rate for people with localized Merkel cell carcinoma is around 64%, meaning that 64% of people with this type of cancer are still alive 5 years after diagnosis. However, if cancer has spread to nearby lymph nodes or other parts of the body, the 5-year survival rate drops to around 46%.
It’s worth noting that these survival rates are based on large groups of people with Merkel cell carcinoma and do not take into account individual factors such as age, overall health, and the specific characteristics of cancer.