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Merkel Cell Carcinoma of Skin

Last updated Jan. 31, 2019


Microscopic pathology image showing Merkel Cell Carcinoma of Skin.

What are the other Names for this Condition? (Also known as/Synonyms)

  • Cutaneous Neuroendocrine Carcinoma
  • Primary Small Cell Carcinoma of Skin
  • Trabecular Skin Carcinoma

What is Merkel Cell Carcinoma of Skin? (Definition/Background Information)

  • Merkel Cell Carcinoma (MCC) is a rare cancer of the skin, which usually occurs in elderly individuals (in their late 60s)
  • The cancer can be fatal, if it is not treated promptly
  • This cancer occurs in sun-exposed areas of the body. The most common area of occurrence being the head and neck region

Who gets Merkel Cell Carcinoma of Skin? (Age and Sex Distribution)

  • Merkel Cell Carcinoma usually occurs in elderly individuals; an increased incidence being associated with adults who are in their 60s
  • Both males and females are affected by the tumor, though it is more common in men than women (in a 2:1 ratio)
  • A majority of the tumors occur in the Caucasian population, and it is very rare amongst the African-American population
  • Merkel Cell Carcinoma is seen all over the world; there is no particular geographical restriction

What are the Risk Factors for Merkel Cell Carcinoma of Skin? (Predisposing Factors)

The risk factors for Merkel Cell Carcinoma include:

  • Sun exposure
  • HIV and AIDS affected individuals
  • Solid organ (kidney, heart, lung, and liver) transplant patients
  • Individuals who remain immunodeficient for long periods of time; such as those undergoing chronic steroidal therapy, those with autoimmune disorders, etc.

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases ones chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Merkel Cell Carcinoma of Skin? (Etiology)

  • The exact cause for Merkel Cell Carcinoma is unknown. Research is being currently conducted to determine the exact cause of the condition
  • Some cases of MCC have shown chromosomal abnormalities in chromosome 1 (in the short arm of chromosome 1). Such chromosomal abnormalities have been noted in cancers, such as neuroblastoma and melanoma. Some researchers believe that these tumor groups may be related to each other
  • Besides, over half of all MCCs have a specific type of chromosomal abnormality, called trisomy of chromosome 6
  • The gene responsible for the development of Merkel Cell Carcinoma is currently unknown

What are the Signs and Symptoms of Merkel Cell Carcinoma of Skin?

The following are the clinical signs and symptoms of Merkel Cell Carcinoma:

  • A single painless dome-shaped nodule, or occasionally the nodule may be present as a plaque, which is reddish in color. The skin over the plaques may ulcerate
  • The mass/nodule and the reddish discolored area (plaque), is not itchy
  • The mass grows rapidly. In just a matter of few weeks or months, the tumor can become large and readily noticeable
  • The most common areas of skin that are involved with MCC include the head and neck region, arms, and legs
  • In a majority of the cases the tumor size measures 0.5 cm to 2 cm

How is Merkel Cell Carcinoma of Skin Diagnosed?

The diagnosis of Merkel Cell Carcinoma is as follows:

  • Medical examination with a thorough physical examination
  • Skin biopsy of the lesion (mass); the skin biopsy is examined by a pathologist under the microscope, to arrive at a definitive diagnosis
  • Chest x-ray
  • CT scan of chest, abdomen

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Merkel Cell Carcinoma of Skin?

The complications of Merkel Cell Carcinoma include:

  • Metastasis (spreading of the cancer) to distant organs
  • Recurrence of Merkel Cell Carcinoma at the original tumor site, after initial surgery

How is Merkel Cell Carcinoma of Skin Treated?

Treatment measures for Merkel Cell Carcinoma:

  • After the initial biopsy (to aid in diagnosis), the mass is completely excised through surgical resection. Occasionally, a dissection of the lymph nodes in the neck region, may also have to be performed
  • In case of metastatic Merkel Cell Carcinoma, chemotherapy and radiation therapy, may have to be additionally administered

How can Merkel Cell Carcinoma of Skin be Prevented?

Currently, there are no known methods to prevent Merkel Cell Carcinoma.

What is the Prognosis of Merkel Cell Carcinoma of Skin? (Outcomes/Resolutions)

  • The prognosis of Merkel Cell Carcinoma depends upon the stage of the tumor. If the tumor is localized to the skin, then complete excision of the tumor through surgery is curative
  • If the tumor is of a higher stage (if tumor has spread to other parts of the body), then the prognosis is guarded
  • The prognosis is worse if the tumor is diagnosed in an older adult, is located in the head and neck region, has a size greater than 2 cm, and if the individual is immunocompromised
  • If the tumor has a fast growth rate, as determined during a microscopic examination (by the pathologist), then the tumor outcome may be worse
  • If the tumor has spread into the blood vessels, termed angiolymphatic invasion (as established upon a microscopic examination by a pathologist), then this factor also makes for a poor prognosis

Additional and Relevant Useful Information for Merkel Cell Carcinoma of Skin:

  • Approximately 500 new cases of Merkel Cell Carcinomas are diagnosed in the United States each year
  • The pathologist may perform additional testing to help with the diagnosis. Such tests may include immunostains, such as cytokeratins, epithelial membrane antigen, cytokeratin 20, thyroid transcription factor I (TTF-1), chromogranin, synaptophysin, neuron specific enolase, Bombesin, somatostatin, calcitonin, gastrin, CD117, and CD 99. The tumor is usually positive for the above mentioned immunochemical stains
  • The tumor is negative for immunostains, such as leukocyte common antigen and S100 protein. The staining pattern helps a pathologist arrive at a correct diagnosis

What are some Useful Resources for Additional Information?

References and Information Sources used for the Article:

Helpful Peer-Reviewed Medical Articles:

Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: June 9, 2013
Last updated: Jan. 31, 2019