DermNet NZ


Merkel cell carcinoma


Merkel cell carcinoma is believed to arise from Merkel cells, which are pressure receptors in the skin.

How gets Merkel cell carcinoma?

Merkel cell carcinoma has an estimated incidence of 0.23 per 100,000 people in Caucasian populations. Increasing numbers of Merkel cell carcinomas have been reported by some centres in recent years. Merkel cell carcinoma is more common in the elderly, with most cases occuring after the age of 50. It is slightly more common in men, and occurs on parts of the body commonly exposed to sunlight, most often the head and neck. It is also more common and more serious in those that are immune suppressed, such as patients with solid organ transplants, human immunodeficiency virus (HIV) infection, haematological malignancy or on drugs such as azathioprine.

What are the clinical features of Merkel cell carcinoma?


Merkel cell cancers spread through the lymphatic system and multiple smaller seedlings can develop around the main tumour (local recurrence). Merkel cell carcinoma may also spread to lymph nodes in the neck, axillae and groin. This is more likely in thicker tumours.

Merkel cell carcinoma
Image supplied by Bob Rossborough
Merkel cell carcinoma
Image supplied by Catherine Skiens
Merkel cell carcinoma
Merkel cell carcinoma Merkel cell carcinoma
Image supplied by Dr Slavko Doslo
Merkel cell carcinoma
Also, lower lid: squamous cell carcinoma
Merkel cell carcinoma

What causes Merkel cell carcinoma?


Ultraviolet radiation has been implicated as a factor in developing Merkel cell carcinoma, due to the occurrence of the tumour on sun exposed skin. Immunosuppression is an important factor for the development of Merkel cell carcinomas.

How is Merkel cell carcinoma diagnosed?



A specific Merkel cell carcinoma staging system is pubished by the American Joint Committee on Cancer.


What is the treatment of Merkel cell carcinoma?

Localised disease
Surgical excision is the main treatment of primary Merkel cell carcinoma. A wide area surrounding the cancer is also removed.

After removal of large lesions (eg >2 cm), the site may also be treated with radiotherapy post-operatively. Radiation treatment leads to increased local and regional disease control and higher long-term survival rates.


Disease involving regional lymph nodes

Distant metastatic disease

Consensus treatment guidelines are published by the National Comprehensive Cancer Network.

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Author: Mathew Ludgate MBChB, Dept of Dermatology Greenlane Hospital Auckland. Updated by A/Prof Amanda Oakley, Hamilton, New Zealand. September 2014.

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