Merkel Cell Skin Cancer: What Is It, Symptoms and Causes

Merkel cell skin cancer is a rare but aggressive form of skin cancer that often appears as a painless, fast-growing lump on sun-exposed areas of the skin. While it may not be as widely recognized as melanoma or basal cell carcinoma, it’s crucial to understand its severity.

What is Merkel Cell Skin Cancer?

Merkel cell skin cancer, also known as Merkel cell carcinoma, is a type of cancer that starts in the skin’s Merkel cells. These cells are generally located close to the nerve endings and are responsible for the sense of touch. This type of cancer is often characterized by fast-growing tumors that primarily occur in the head, neck, and arms but can appear anywhere on the body.

The cancer is aggressive and has a high probability of spreading to other parts of the body. The five-year survival rate drops drastically if the cancer spreads, making it essential for early diagnosis and prompt treatment. However, due to its rarity, the disease often goes unnoticed or is misdiagnosed, which significantly impacts the survival rates.

Symptoms of Merkel Cell Skin Cancer

Early Detection and Common Signs

Merkel cell skin cancer, also known as Merkel cell carcinoma, is a rare and aggressive type of skin cancer that primarily affects the elderly and immunocompromised individuals. Early detection is crucial for better prognosis and treatment outcomes. The most common sign of Merkel cell skin cancer is the sudden appearance of a fast-growing, painless nodule (lump) on the skin.

This nodule is usually red or violet in color and has a shiny appearance. Although it may occur anywhere on the body, the cancer is commonly found on sun-exposed areas such as the face, neck, and arms. Unlike other skin cancers, which may develop gradually over time, Merkel cell skin cancer tends to grow quickly, making rapid diagnosis and treatment essential.

Due to its aggressive nature, Merkel cell skin cancer requires immediate medical attention. The appearance of a new lump, especially one that grows rapidly, should never be ignored. This is even more crucial for individuals with risk factors like old age, weak immune systems, or extensive sun exposure history.

While the aforementioned nodule is the most characteristic symptom, the tumor may also itch or produce a burning sensation. However, these symptoms are not as common and the absence of discomfort does not rule out the presence of Merkel cell skin cancer.

Uncommon Symptoms and Metastasis

As the cancer progresses, more severe symptoms can manifest. In advanced stages, Merkel cell skin cancer may metastasize (spread) to other parts of the body, such as the lymph nodes, lungs, brain, or bones. When the cancer spreads to the lymph nodes, it can cause them to swell, leading to noticeable lumps under the skin or deeper within the body. These lumps are often painless, much like the original skin tumor, and they may be overlooked if not actively monitored.

Furthermore, metastasis to other organs can result in a variety of symptoms depending on the affected organ. For example, if the cancer spreads to the lungs, symptoms like coughing, difficulty breathing, and chest pain may occur. When the brain is involved, neurological symptoms such as headaches, dizziness, and vision problems may manifest. Due to the severity of these symptoms and the aggressive nature of Merkel cell skin cancer, immediate consultation with a healthcare provider is imperative for diagnosis and to initiate appropriate treatment.

Causes of Merkel Cell Skin Cancer

Known Risk Factors and Mechanisms

Merkel cell skin cancer, also referred to as Merkel cell carcinoma, is a rare and aggressive form of skin cancer. Its exact cause remains largely unknown, but several risk factors have been identified. The most significant risk factor is ultraviolet (UV) radiation exposure, particularly from sunlight.

The carcinogenic effects of UV radiation can damage the DNA of skin cells, including Merkel cells, thereby increasing the risk of malignant transformation. This is one reason why the disease is often found on sun-exposed areas of the skin, such as the face, neck, and arms.

People with a weakened immune system are also at an elevated risk of developing Merkel cell skin cancer. Conditions that impair the immune system such as HIV/AIDS, organ transplantation, and certain autoimmune diseases can make it more difficult for the body to fight off cancer cells.

Long-term use of immunosuppressive medications, usually given to organ transplant recipients to prevent graft rejection, can similarly weaken the immune system and contribute to the risk. Older age is another significant risk factor, as the majority of Merkel cell skin cancer cases are diagnosed in people over the age of 50. The risk increases further with advancing age, and the disease is more common in men than in women.

Viral Infection and Genetic Predisposition

One notable cause that has been identified is the Merkel cell polyomavirus (MCPyV). This virus has been found in a substantial number of Merkel cell carcinoma tumors. While the virus is common and usually harmless, in rare cases it can integrate into the host’s DNA and initiate cancerous changes. However, not everyone with the virus will develop cancer, indicating that other factors are also at play.

Genetic factors might also contribute to the risk of developing Merkel cell skin cancer, although the genetic basis is not well-understood. Individuals with a family history of skin cancer or who have certain hereditary conditions that make them more susceptible to skin malignancies might be at an elevated risk. However, Merkel cell skin cancer is so rare that it has been challenging for researchers to definitively establish a genetic link.

In summary, while the exact cause of Merkel cell skin cancer is not fully understood, a combination of environmental, immunological, and possibly genetic factors appear to contribute to its onset. Understanding these causes and risk factors can help in early diagnosis and prevention, which are crucial given the aggressive nature of this cancer.

Diagnosis of Merkel Cell Skin Cancer

Initial Evaluation and Physical Examination

Diagnosing Merkel cell skin cancer (Merkel cell carcinoma) is a multi-step process that involves various diagnostic tests and procedures. The first step in the diagnosis often starts with a thorough physical examination by a healthcare provider, who may also review the patient’s medical history, including any risk factors for skin cancer.

During the examination, particular attention is paid to the skin, focusing on the appearance, size, shape, and color of any unusual growths, lumps, or nodules. Given the aggressive nature of this type of cancer, any suspicious skin lesions require prompt further investigation.

For a more detailed evaluation, dermatologists often use a technique known as dermatoscopy (also called dermoscopy), which involves examining the skin using a specialized magnifying lens. This allows the healthcare provider to view skin abnormalities more clearly and decide whether further diagnostic tests are necessary. It’s crucial to note that while physical examinations and dermatoscopy can suggest the presence of Merkel cell skin cancer, they cannot confirm the diagnosis. For definitive diagnosis, more specific tests are required.

Biopsy and Histological Analysis

A biopsy is the most reliable method for confirming the diagnosis of Merkel cell skin cancer. During a biopsy, a sample of the suspicious skin tissue is removed and sent to a laboratory for histological analysis. The tissue is examined under a microscope to look for cancerous cells characteristic of Merkel cell carcinoma.

There are different types of biopsies that may be used, such as excisional biopsy, where the entire lump is removed, or incisional biopsy, where only a portion of the suspicious area is taken. The type of biopsy performed often depends on the size and location of the lesion.

After the biopsy, if Merkel cell carcinoma is confirmed, additional tests are typically conducted to determine the stage of the cancer, which helps guide treatment options. Staging tests may include imaging studies like X-rays, MRI (Magnetic Resonance Imaging), and CT (Computed Tomography) scans, which can help identify whether the cancer has spread to other parts of the body. In some cases, a sentinel lymph node biopsy may also be performed to assess if cancer cells have spread to nearby lymph nodes.

Overall, the diagnostic process for Merkel cell skin cancer is a comprehensive one that involves a series of steps, each designed to add valuable information for treatment planning. Early and accurate diagnosis is crucial for effective management and improving outcomes, especially given the aggressive nature of this type of skin cancer.

Appearance of Merkel Cell Cancer

Visual Characteristics on the Skin

Merkel cell cancer, also known as Merkel cell carcinoma, typically manifests as a single, painless lump (nodule) on the skin. It is important to note that the nodule can have varying appearances but generally exhibits certain characteristic features. One of the most distinguishing aspects is its rapid growth. Within weeks or a few months, the nodule can increase substantially in size, drawing attention due to its quick expansion.

The lump often has a shiny and smooth surface with a red or violet hue, but it can also appear flesh-colored. Because of its glossy and dome-like presentation, it can sometimes be mistaken for other types of skin growths, such as cysts, benign moles, or other forms of skin cancer like melanoma or basal cell carcinoma.

However, what sets Merkel cell cancer apart from other skin conditions is its aggressive nature and its tendency to appear in sun-exposed areas like the face, neck, and arms. The lesion might not produce any symptoms like itching or pain, although in some cases, a mild sensation of discomfort or itching may be present.

Unusual Presentations and Varied Appearances

While the most typical presentation is that of a rapidly enlarging nodule, Merkel cell cancer can sometimes exhibit unusual characteristics that make it challenging to identify solely based on its appearance. For instance, the lesion might be flat rather than raised, or it could have an irregular surface.

It could also appear ulcerated or broken, especially as the disease progresses. Some Merkel cell carcinomas may have a different coloration, possibly appearing blue, pink, or flesh-colored, adding to the complexity of making a visual identification.

Given the variability in its appearance and the severe implications of a delayed diagnosis, it’s crucial to consult a healthcare provider if you notice any new or changing skin growths. The definitive diagnosis of Merkel cell cancer usually involves a thorough examination, including a biopsy and microscopic examination, to distinguish it from other skin conditions.

Growth Rate of Merkel Cell Skin Cancer

Rapid Progression and Early Stages

Merkel cell skin cancer, also known as Merkel cell carcinoma, is known for its aggressive nature and rapid growth rate. Unlike other forms of skin cancer that may take months or even years to show significant changes, Merkel cell skin cancer can grow and spread within weeks to a few months.

The initial appearance of a painless, red or violet, and shiny nodule on the skin can quickly evolve into a larger mass. This swift growth rate makes timely diagnosis and intervention crucial for effective treatment and a better prognosis.

In the early stages, the nodule may be small and not cause any discomfort, leading some people to underestimate its seriousness. However, due to its aggressive characteristics, the cancer can quickly progress from a localized stage to an advanced stage, affecting the lymph nodes and potentially metastasizing to other organs. In the span of weeks or a few months, what might have initially seemed like a harmless skin lesion could become a severe medical condition requiring immediate and intensive treatment.

Late Stages and Metastasis

As the disease advances, the risk of metastasis where the cancer spreads to other parts of the body—increases significantly. When Merkel cell skin cancer metastasizes, it commonly involves the lymph nodes first. From there, it can spread to other organs such as the lungs, liver, brain, and bones. The speed of this metastatic spread can also be rapid, consistent with the aggressive nature of the primary skin lesion.

The quick metastatic potential makes Merkel cell skin cancer one of the most aggressive types of skin cancer. Once the cancer has spread, treatment becomes more complex and the prognosis worsens. This underscores the importance of early detection and immediate medical intervention to manage the disease effectively.

Given these factors, any new or rapidly growing skin nodules should be promptly evaluated by a healthcare provider for diagnosis and appropriate treatment planning. Because of the speed at which Merkel cell skin cancer grows and spreads, waiting or adopting a “wait-and-see” approach is not advisable.

Bleeding in Merkel Cell Skin Cancer

Common Presentation and the Potential for Bleeding

Merkel cell skin cancer, or Merkel cell carcinoma, commonly presents as a fast-growing, shiny, and smooth nodule that is usually red or violet in color. While bleeding is not considered a hallmark feature of Merkel cell skin cancer, it is not unheard of. As the tumor grows rapidly, the skin over the nodule may become fragile or ulcerated, which could potentially result in bleeding. However, the likelihood of bleeding often depends on several factors, including the stage of the cancer, its size, and its location on the body.

Even though bleeding can occur, it’s important to note that the absence of bleeding does not rule out Merkel cell carcinoma. Many cases present without any bleeding, and the nodule may be entirely asymptomatic, meaning it doesn’t cause pain or discomfort. Therefore, the absence of bleeding should not be used as a reassurance that the growth is benign or non-cancerous.

Importance of Medical Evaluation

If a nodule does start to bleed, it is crucial to seek medical evaluation immediately, as bleeding could indicate an advanced stage of the disease or an ulcerated tumor. Moreover, bleeding could also complicate the condition by introducing the risk of infection, which could further accelerate the progression of the disease. Therefore, any new or rapidly growing skin nodules, whether they are bleeding or not, should be promptly evaluated by a healthcare provider for diagnosis and appropriate treatment.

Given the aggressive nature of Merkel cell skin cancer and its rapid growth rate, early detection and intervention are essential for a better prognosis. A definitive diagnosis often involves a biopsy of the suspicious skin tissue, followed by microscopic examination to confirm the presence of Merkel cell carcinoma. Additional tests may be conducted to determine the stage of the cancer and whether it has spread to other parts of the body, guiding the treatment plan accordingly.

Final Thoughts

Merkel cell skin cancer is a rare but highly aggressive form of cancer that requires immediate attention. Its rapid growth rate and high probability of spreading to other parts of the body make early diagnosis and prompt treatment crucial for survival.

Unfortunately, due to its rarity, it is often misdiagnosed, leading to delayed treatment. Therefore, if you notice any sudden lump or changes in your skin, especially in sun-exposed areas, consult a healthcare professional immediately for an accurate diagnosis and appropriate treatment. Awareness and early intervention are key to improving survival rates for this serious condition.


  1. What Does Merkel Cancer Look Like?

    Merkel cell carcinoma often appears as a lump that’s flesh-colored or in shades of red, pink, or purple. The lump is usually firm, shiny, and grows rapidly.

  2. How Fast Does Merkel Skin Cancer Grow?

    Merkel cell skin cancer grows at a rapid pace, often doubling in size within weeks. This fast growth rate makes early detection and treatment vital.

  3. Does Merkel Cell Carcinoma Bleed?

    Although not a common symptom, some Merkel cell carcinomas may ulcerate or bleed, particularly in the later stages.