Non-melanoma skin cancer

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Merkel cell carcinoma

Merkel cell carcinoma is a rare type of non-melanoma skin cancer. It starts in Merkel cells, which are found in the deepest part of the top or outer layer of skin (epidermis) and in the hair follicles (small sacs where hair starts to grow). Merkel cells are close to nerves and help give the sense of touch. They also make hormones.

Merkel cell carcinoma usually starts on areas of skin exposed to the sun, especially the head, neck, arms and legs. It grows and spreads quickly (is aggressive).

Merkel cell carcinoma is also called neuroendocrine cancer of the skin or trabecular carcinoma.

Signs and symptoms

Merkel cell carcinoma usually appears as a firm and raised lump on the skin. The lump can be red or purple and it is not usually painful.

Since Merkel cell carcinoma tends to grow and spread quickly, new lumps may form on nearby skin. Lymph nodes may also become larger than normal, especially in the neck or under an arm.


The tests used to diagnose Merkel cell carcinoma usually include a physical exam, skin exam and skin biopsy of the lump. The skin biopsy is done using a shave biopsy, punch biopsy, incisional biopsy or excisional biopsy. If Merkel cell carcinoma is diagnosed, then other tests, such as a CT scan and an MRI, may be done to check if the cancer has spread to other parts of the body. You may also be offered a sentinel lymph node biopsy. This test can give the doctor information about how quickly the cancer is growing and spreading and will help plan treatment.

Find out more about these tests and diagnosis of non-melanoma skin cancer.


Staging is a way to describe or classify a cancer based on the extent of cancer in the body. Extent includes the size of the tumour and where the cancer is. Your healthcare team uses the stage to plan treatment and estimate your prognosis.

The TNM staging system is used for Merkel cell carcinoma. Each stage is given a number from 0 to 4. Stages 1 to 4 are usually given as the Roman numerals I, II, III and IV. Generally, the higher the number, the more the cancer has spread.

Merkel cell carcinoma is staged differently than other non-melanoma skin cancers.






The cancer is only in the top or outer layer of the skin (epidermis). Stage 0 is also called carcinoma in situ.

IA or IB




The tumour is 2 cm or smaller.


T2 or T3



The tumour is larger than 2 cm.





The tumour has spread to nearby bone, muscle, cartilage or fascia (connective tissue that wraps around muscles, nerves, blood vessels and organs).


any T

N1a, N1b or N2


The tumour is any size. It may have spread to nearby bone, muscle, cartilage or fascia.

The cancer has spread to nearby lymph nodes. There may be a very small amount of cancer in a lymph node (N1a) or a larger amount of cancer in many lymph nodes (N1b). Another skin tumour may have started to spread to lymph nodes (N2).


any T

any N


The tumour is any size. It may have spread to nearby bone, muscle, cartilage or fascia.

The cancer may have spread to nearby lymph nodes.

The cancer has spread to other parts of the body, such as tissues under the skin, distant lymph nodes, the lungs or the liver.

Treatments for Merkel cell carcinoma

You may be offered one or more of the following treatments for Merkel cell carcinoma. Your healthcare team will suggest treatments based on the stage and where the cancer started. They will work with you to develop a treatment plan.


The type of surgery done depends on the stage (the size of the cancer and where it is).

Wide local excision removes the cancer along with some normal tissue around it (called the surgical margin). It is the standard type of surgery used when the Merkel cell carcinoma is only in the skin and has not spread to other parts of the body.

Mohs surgery removes the cancer in layers, little by little, until no cancer remains. It may be done when doctors want to leave as much normal tissue as possible (called tissue sparing). For example, Mohs surgery may be done for Merkel cell carcinoma on the face.

Lymph node dissection removes lymph nodes that may contain cancer. It is done when the doctor can feel enlarged lymph nodes or the sentinel lymph node biopsy shows that the sentinel lymph node contains cancer. A lymph node dissection can be done after the primary tumour has been removed.

Radiation therapy

External beam radiation therapy uses a machine to direct a beam of radiation to the cancer and some of the tissue around it.

Radiation therapy can be used after surgery to destroy any remaining cancer cells and help reduce the risk of the cancer coming back, or recurring (called adjuvant therapy). Sometimes the radiation is directed toward nearby lymph nodes. It can also be used to treat Merkel cell carcinoma that has come back after surgery. Radiation therapy may be used to relieve symptoms of advanced Merkel cell carcinoma (called palliative therapy).


Chemotherapy uses drugs to treat Merkel cell carcinoma. It is most often used to treat stage IV Merkel cell carcinoma to help shrink the cancer, to slow the growth and spread of the cancer and to relieve symptoms. It may be given alone or with other treatments.

The most common chemotherapy treatment for Merkel cell carcinoma is cisplatin (Platinol AQ) or carboplatin (Paraplatin, Paraplatin AQ), which may be combined with etoposide (Vepesid, VP-16). Topotecan (Hycamtin) may be used alone in some cases, such as for older people. Chemotherapy is usually given with a needle into a vein (intravenously) every few weeks. Treatment usually continues as long as the cancer doesn’t grow or spread any farther and you can cope with the side effects.

Clinical trials

You may be asked if you want to join a clinical trial for skin cancer. Find out more about clinical trials.


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