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Merkel Cell Carcinoma

what is skin cancer, how is skin cancer diagnosed, cutaneous paraneoplastic syndrome, basal cell carcinoma, squamous cell carcinoma, melanoma, Merkel cell carcinoma
What is Merkel Cell Carcinoma?

Merkel cell carcinoma is a very rare type of skin cancer that forms with Merkel cells, found on the top layer of skin, grow out of control. It usually starts on areas of the skin that have received a lot of sun exposure, especially the head and neck, but can also affect the arms, legs and trunk.
Because Merkel cell carcinoma tends to grow very quickly and metastasize early – to the lymph nodes, other parts of the skin, lungs, brain, bones and other organs – you should have anything suspicious checked immediately. 

Symptoms of Merkel cell carcinoma

Merkel cell carcinoma usually appears as a single painless lump on sun-exposed skin. However, other conditions may cause the same symptoms so it’s best to make an appointment and come in and see us, especially if you notice any changes in your skin.


Merkel cell carcinoma usually appears on sun-exposed skin as a single lump that is:

  • Fast-growing

  • Painless

  • Firm and dome-shaped or raised

  • Red or violet in color


Tests and procedures that examine the skin are used to find and diagnose Merkel cell carcinoma.

  • Physical exam and history: An exam of the body to check general signs of health, including checking for signs of disease, such as lumps or anything else that seems unusual. A history of your health habits and past illnesses and treatments will also be taken.

  • Full-body skin exam: The skin is carefully checked for bumps or spots that look abnormal in color, size, shape, or texture. The size, shape, and texture of the lymph nodes will also be checked.

  • Biopsy: The removal of cells or tissues so they can be viewed under a microscope by a pathologist to check for signs of cancer.


Prognosis also depends on how deeply the tumor has invaded into the skin. 

Risk factors

Risk factors for Merkel cell carcinoma include the following:

  • Having previous exposure to a lot of natural sunlight

  • Having previous exposure to artificial sunlight, such as from tanning beds or psoralen and ultraviolet A (PUVA) therapy for psoriasis

  • Having an immune system weakened by disease, such as chronic lymphocytic leukemia or HIV infection

  • Taking drugs that make the immune system less active, such as after an organ transplant

  • Having a history of other types of cancer

  • Being older than 50 years, male, or white



Treatment is generally based on the stage of the disease. As with many other cancers, treatment options for Merkel cell carcinoma include:

  • Surgical treatment of the primary lesion and any lymph nodes also indicated

  • Radiation therapy

  • Chemotherapy


At all stages of Merkel cell cancer, complete excision of the primary lesion, verified by pathologic examination, is recommended. When the lymph nodes are involved, surgical excision or radiation treatment to the involved nodes should be carried out because it diminishes the risk of recurrence in the affected region. In most cases it is important for patients with no obvious lymph node disease to undergo sentinel lymph node biopsy to determine their prognosis and the necessity of further treatment. Radiation therapy is typically recommended for the site of the primary lesion when the risk of recurrence is high. And chemotherapy is usually reserved for patients with metastatic cancer of the liver, lungs and breast.

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