Merkel cell Carcinoma, also known as Trabecular carcinoma can be considered as a rare type of skin cancer where the proliferation of cancer cells happens on the skin exposed to the sun mainly the face, head or neck, arms and legs. This type of carcinoma is often referred to as Neuroendocrine carcinoma of the skin since the cells are much alike to the nerve cells and hormone-making cells. Merkel cell Carcinoma generally originates at the base of the epidermis and appear as painless bluish-pink, red, or purple shiny nodules, which can sometimes turn into ulcers and sores and bleed as well.
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These types of tumours are extremely fast-growing and easily spread in the form of new lumps to the nearby lymph nodes and other parts of the body.

Causes

Just like any other form of cancer, the exact cause of Merkel cell carcinoma is yet unknown, but reports suggest that they usually begin in the Merkel cells, which are found at the base of the epidermis, the outermost layer of the skin. When the normal merkel cells which are connected to the nerve endings responsible for the sense of touch, have a change or mutation in the DNA, it leads to abnormal growth of cells both in size and number. These cells don't die and accumulate together to form tumorous growth.

Although there are no solid proofs, in some cases Merkel cell carcinoma has been found associated with people suffering from a type of viral infection, named Merkel cell polyomavirus which usually resides on the skin.

Risk Factors

The following causative factors increase the risk of Merkel cell carcinoma. They are:

Age: Although it can happen at any age, Merkel cell carcinoma is more likely to get diagnosed in older people above the age of 50.

Skin colour: People with light-toned skin are more at risk of getting Merkel cell carcinoma than their dark-skinned counterpart.

Gender: More common in males than in females.

Over-exposure to natural or artificial sunlight: An excessive exposure to harmful UV radiation from direct sunlight or tanning beds can damage the cellular DNA while making one prone to Merkel cell carcinoma.

Weakened immune system: People suffering from a weakened immune system such as those diagnosed with HIV infection or AIDS, or Chronic leukemia or the ones taking immunity suppressing drugs are more at risk of developing this type of skin cancer.

History of other skin cancers: Diagnosed previously with any other form of skin cancer such as basal cell or squamous cell carcinoma increases the chances of Merkel cell carcinoma.
Also Read: Basal Cell Carcinoma: Causes, Symptoms And Treatment

Symptoms

It is quite difficult to diagnose Merkel cell carcinoma in the earlier stages since the symptoms are quite similar to that of other skin conditions. Typically, common signs and symptoms arise in the form of reddish-purple, painless, firm fast-spreading nodules and are generally found in the face, neck, arms and legs.

Diagnosis And Treatment

On noticing small bumps that may change in size, shape, colour  and seem to bleed or grow fast, do consult a doctor right away. The doctor usually does a thorough physical checkup to look for any lumps, lesions, moles or irregular nodules followed by acknowledging the patient's past medical history, history of extreme sun exposure and conduct some diagnostics. These include:

• Skin biopsy
• Sentinel lymph node biopsy
• Imaging techniques like X-ray, CT-scan (computed tomography), PET-scan (positron emission tomography), and MRI-scan (magnetic resonance imaging)

Treatment

The available treatment options usually depend upon the severity, extent and form of cancer. It includes:

• Surgery
• Radiation therapy
• Chemotherapy
• Immunotherapy