7 Warning Signs and Symptoms of Merkel Cell Carcinoma You Should Know

Merkel cell carcinoma (MCC) is a rare and aggressive type of skin cancer that develops in Merkel cells, which are found in the top layer of the skin near nerve endings. These specialized cells are responsible for our sense of light touch. While uncommon, Merkel cell carcinoma is considered one of the most dangerous forms of skin cancer due to its tendency to grow quickly and spread to other parts of the body.

This condition primarily affects older adults, typically those over 50 years of age, and individuals with fair skin who have had significant sun exposure throughout their lives. The cancer often appears on sun-exposed areas of the body, particularly the head, neck, and arms. Early detection is crucial for successful management, making it essential to recognize the warning signs and symptoms of this serious condition.

Understanding the symptoms of Merkel cell carcinoma can help you identify potential problems early and seek prompt medical attention. Below are the seven most common warning signs that may indicate the presence of this aggressive skin cancer.

1. A Painless, Fast-Growing Nodule or Lump

The most characteristic symptom of Merkel cell carcinoma is the appearance of a painless nodule or bump on the skin. This growth typically develops rapidly, often within a few weeks to months, which distinguishes it from other, more benign skin conditions.

The nodule usually has the following characteristics:

• Firm and dome-shaped appearance
• Smooth surface texture
• Size ranging from less than half an inch to over an inch in diameter
• Fast growth rate that may be noticeable week to week
• Does not cause pain or tenderness when touched

This rapid growth is particularly concerning and should prompt immediate medical evaluation. Unlike other skin lesions that may take months or years to change, a Merkel cell tumor can double in size within weeks. The painless nature of these growths often leads people to ignore them initially, which can delay diagnosis and treatment.

2. Red, Pink, or Purple Skin Discoloration

Merkel cell carcinoma tumors often display distinctive coloration that can help differentiate them from other skin conditions. The affected area typically appears red, pink, purple, or even blue in color, though the exact shade can vary between individuals.

This discoloration occurs because:

• The tumor has a rich blood supply, causing increased vascularity
• The cancer cells are located close to the skin surface
• The overlying skin becomes thin and translucent
• Blood vessels within and around the tumor become visible

The color may be uniform throughout the lesion or vary in intensity across different areas. Some tumors may also have a shiny or pearly appearance that reflects light. This coloration is particularly noticeable in fair-skinned individuals but can be present in all skin types. The distinctive color, combined with rapid growth, should raise suspicion for Merkel cell carcinoma and warrant dermatological examination.

3. A Shiny or Pearly Appearance

Many Merkel cell carcinomas exhibit a characteristic shiny, glossy, or pearly surface that can resemble a blister or cyst. This distinctive appearance is one of the key visual clues that help dermatologists identify potential cases of this rare cancer.

The shiny appearance results from several factors:

• The tumor grows beneath a thin layer of stretched skin
• The epidermis (outer skin layer) becomes thinned and taut over the rapidly expanding mass
• Light reflects off the smooth, tight surface of the lesion
• The tumor may have minimal overlying skin texture or hair follicles

This pearly or translucent quality can sometimes cause confusion with other conditions, such as basal cell carcinoma, amelanotic melanoma, or even benign cysts. However, the combination of a shiny appearance with rapid growth and firm texture is particularly suggestive of Merkel cell carcinoma. Patients often describe the lesion as looking “water-filled” or “bubble-like,” though unlike true blisters, these growths are solid and firm to the touch.

4. A Non-Healing Sore or Ulceration

As Merkel cell carcinoma progresses, the overlying skin may break down, leading to ulceration or the formation of a sore that doesn’t heal. This symptom typically occurs as the tumor outgrows its blood supply or when the rapidly dividing cancer cells break through the skin surface.

Characteristics of MCC-related ulceration include:

• A wound or sore that persists for weeks without improvement
• Bleeding that occurs spontaneously or with minimal trauma
• Crusting or scabbing that repeatedly forms and falls off
• Drainage or oozing from the lesion
• Surrounding inflammation or redness

The presence of an ulcerated area on a growing skin lesion is particularly concerning. While many benign conditions can cause non-healing wounds, when combined with other features of Merkel cell carcinoma—such as rapid growth, firm texture, and unusual coloration—ulceration strongly suggests an aggressive process requiring immediate evaluation. The wound may be painless or minimally uncomfortable, which can falsely reassure patients and delay seeking medical care.

5. Enlarged Lymph Nodes

One of the most serious symptoms of Merkel cell carcinoma is the enlargement of lymph nodes near the primary tumor site. This occurs when cancer cells spread through the lymphatic system, a common pathway for MCC metastasis. Lymph node involvement is found in approximately 30% of patients at the time of initial diagnosis.

Key aspects of lymph node enlargement in MCC include:

• Swollen, firm lumps in the neck, armpits, or groin area
• Lymph nodes that feel hard and may be fixed in place rather than mobile
• Usually painless, though some discomfort may be present
• Progressive enlargement over time
• Location corresponding to the drainage pathway from the primary tumor site

For example, if the primary Merkel cell tumor is on the face or scalp, the lymph nodes in the neck may become enlarged. If the tumor is on the arm, the axillary (armpit) lymph nodes may be affected. This regional lymph node involvement significantly impacts prognosis and treatment planning. Any unexplained lymph node swelling, especially when accompanied by a suspicious skin lesion, requires prompt medical evaluation and possible biopsy to determine if cancer has spread.

6. Lesions on Sun-Exposed Areas

The location of Merkel cell carcinoma is often a diagnostic clue, as these tumors show a strong predilection for sun-exposed areas of the body. Approximately 50% of MCC cases occur on the head and neck region, with another 35-40% appearing on the arms and legs.

Common locations include:

• Face, especially the cheeks, forehead, and around the eyes
• Scalp, particularly in individuals with thinning hair or baldness
• Neck and upper chest area
• Forearms and backs of the hands
• Lower legs, though less common than upper body sites

The strong association with sun-exposed skin reflects the role of chronic ultraviolet (UV) radiation in the development of many Merkel cell carcinomas. Decades of cumulative sun damage can contribute to cellular changes that eventually lead to cancer formation. This pattern is similar to other skin cancers but is particularly pronounced with MCC. However, it’s important to note that Merkel cell carcinomas can occasionally develop on non-sun-exposed areas, including the buttocks, trunk, and even mucous membranes, though this is much less common.

7. Absence of Pain or Other Symptoms

A particularly deceptive characteristic of Merkel cell carcinoma is that it typically causes no pain, itching, tenderness, or other uncomfortable symptoms. This absence of warning sensations is actually a significant symptom itself, as it often leads to delayed diagnosis.

This asymptomatic nature is significant because:

• Patients may not feel urgency to seek medical attention for a painless bump
• The lesion doesn’t interfere with daily activities or cause discomfort
• There is no itching or irritation to draw attention to the area
• The tumor may be discovered accidentally during routine skin checks or by others
• Lack of symptoms does not correlate with the aggressive nature of the cancer

Many people mistakenly believe that serious medical conditions must hurt or cause obvious problems. However, Merkel cell carcinoma demonstrates that dangerous cancers can develop silently. This makes regular skin self-examinations and professional skin checks even more critical, especially for high-risk individuals. Any new, fast-growing skin lesion should be evaluated by a healthcare professional, regardless of whether it causes discomfort. The absence of pain should never be interpreted as a sign that a growth is harmless.

Main Causes of Merkel Cell Carcinoma

While the exact cause of Merkel cell carcinoma is not fully understood, researchers have identified several key factors that significantly increase the risk of developing this rare skin cancer:

Merkel Cell Polyomavirus (MCPyV): This virus is found in approximately 80% of Merkel cell carcinoma tumors and is believed to play a central role in the development of most cases. The virus integrates into the DNA of skin cells and can cause mutations that lead to uncontrolled cell growth. However, MCPyV is very common in the general population, and most people who carry the virus never develop cancer, suggesting that additional factors are necessary for tumor formation.

Excessive Sun Exposure: Chronic exposure to ultraviolet (UV) radiation from the sun or tanning beds is a major risk factor for MCC. Decades of cumulative sun damage can cause DNA mutations in skin cells that may eventually lead to cancer. This explains why Merkel cell carcinoma is most common on sun-exposed areas of the body and in individuals with fair skin who sunburn easily.

Weakened Immune System: Immunosuppression significantly increases the risk of developing Merkel cell carcinoma. This includes people with HIV/AIDS, organ transplant recipients taking immunosuppressive medications, individuals with blood cancers like chronic lymphocytic leukemia, and those on long-term immunosuppressive therapy for autoimmune diseases. A healthy immune system normally eliminates abnormal cells, but when immunity is compromised, cancer cells can grow unchecked.

Advanced Age: The vast majority of Merkel cell carcinoma cases occur in people over 50 years old, with the average age at diagnosis being around 75. Age-related factors include accumulated sun damage over decades, natural decline in immune function, longer exposure time to the Merkel cell polyomavirus, and decreased ability to repair DNA damage in cells.

Fair Skin: Individuals with light skin, blonde or red hair, blue or green eyes, and a tendency to freckle or sunburn have a significantly higher risk of MCC. Melanin provides some natural protection against UV radiation, so people with less pigmentation are more vulnerable to sun-induced DNA damage that can lead to skin cancer.

History of Other Skin Cancers: People who have previously been diagnosed with other types of skin cancer, including basal cell carcinoma, squamous cell carcinoma, or melanoma, have an increased risk of developing Merkel cell carcinoma. This suggests shared risk factors and possible genetic predisposition to skin cancer in general.

Prevention of Merkel Cell Carcinoma

While it may not be possible to completely prevent Merkel cell carcinoma, especially given the role of the Merkel cell polyomavirus, there are several important measures you can take to significantly reduce your risk:

Sun Protection: Since UV radiation is a major risk factor, comprehensive sun protection is the cornerstone of prevention. This includes applying broad-spectrum sunscreen with SPF 30 or higher to all exposed skin, reapplying every two hours and after swimming or sweating, seeking shade during peak sun hours (10 AM to 4 PM), wearing protective clothing including wide-brimmed hats and UV-blocking sunglasses, and avoiding tanning beds and sun lamps entirely.

Regular Skin Examinations: Early detection is critical for better outcomes. Perform monthly self-examinations of your entire body, looking for new growths or changes in existing lesions. Use mirrors or ask a partner to help check hard-to-see areas like your back and scalp. Schedule annual skin checks with a dermatologist, especially if you are over 50, have fair skin, or have a history of significant sun exposure or previous skin cancers. Professional examination can identify suspicious lesions before they become advanced.

Protect Your Immune System: Maintaining a healthy immune system may help your body fight off abnormal cells. This includes eating a balanced diet rich in fruits, vegetables, and whole grains, getting regular exercise, managing stress effectively, getting adequate sleep, avoiding smoking and excessive alcohol consumption, and following your doctor’s recommendations if you have conditions requiring immunosuppressive medications.

Be Vigilant if You’re at Higher Risk: If you have risk factors for Merkel cell carcinoma, such as advanced age, fair skin, a history of extensive sun exposure, immunosuppression, or previous skin cancers, be especially attentive to changes in your skin. Report any new, fast-growing lesions to your healthcare provider immediately, even if they don’t hurt or cause other symptoms.

Education and Awareness: Learn about the signs and symptoms of Merkel cell carcinoma so you can recognize them if they appear. Share this information with family members and friends, especially those in high-risk groups. Awareness can lead to earlier detection and better outcomes.

Frequently Asked Questions

How fast does Merkel cell carcinoma grow?

Merkel cell carcinoma is known for its rapid growth rate. Most tumors develop and become noticeable within a few weeks to a few months. The lesion may double in size in just a matter of weeks, which is much faster than most other skin cancers. This rapid growth is one of the key warning signs that distinguishes MCC from benign skin conditions.

Is Merkel cell carcinoma always visible on the skin?

In the vast majority of cases, Merkel cell carcinoma presents as a visible nodule or lump on the skin surface. However, in rare instances, the first sign may be enlarged lymph nodes, with no obvious skin lesion found initially. The primary tumor may be very small or hidden in an area that’s difficult to see. This is why any unexplained lymph node swelling warrants thorough investigation.

Can Merkel cell carcinoma be confused with other conditions?

Yes, Merkel cell carcinoma can initially resemble several other conditions, including benign cysts, insect bites, basal cell carcinoma, squamous cell carcinoma, amelanotic melanoma, or even a stye when located near the eye. The rapid growth rate and firm texture help distinguish MCC from most benign conditions. Any suspicious lesion should be biopsied for definitive diagnosis.

Who is most at risk for developing Merkel cell carcinoma?

The highest risk group includes adults over 50 years old (especially those over 70), people with fair skin who have had significant lifetime sun exposure, individuals with weakened immune systems (including organ transplant recipients and those with HIV/AIDS or blood cancers), and those with a history of other skin cancers. However, MCC can occasionally occur in younger people or those without obvious risk factors.

What should I do if I notice a fast-growing skin lesion?

Any new, rapidly growing skin lesion should be evaluated by a healthcare provider promptly, ideally a dermatologist. Don’t wait to see if it goes away on its own. Schedule an appointment as soon as possible, and mention the rapid growth rate to ensure timely evaluation. Early detection of Merkel cell carcinoma significantly improves treatment outcomes. A biopsy may be needed to determine whether the lesion is cancerous.

Is Merkel cell carcinoma more dangerous than other skin cancers?

Merkel cell carcinoma is considered one of the most aggressive types of skin cancer. It has a higher tendency to spread to lymph nodes and distant organs compared to more common skin cancers like basal cell carcinoma. However, when detected early and treated appropriately, many patients have good outcomes. The aggressive nature of MCC makes early detection and prompt treatment especially important.

Can Merkel cell carcinoma develop in areas not exposed to the sun?

While MCC most commonly appears on sun-exposed areas like the head, neck, and arms, it can occasionally develop in areas with little or no sun exposure, such as the buttocks, trunk, or even inside the mouth. This suggests that factors other than UV radiation, particularly the Merkel cell polyomavirus, play an important role in some cases. However, sun-exposed locations remain by far the most common sites for this cancer.

Are there any early warning signs before a visible tumor appears?

Unfortunately, Merkel cell carcinoma typically does not cause symptoms before a visible lesion develops. Unlike some cancers that may cause fatigue, weight loss, or other systemic symptoms, MCC usually presents as an asymptomatic skin lesion. This is why regular skin self-examinations and professional skin checks are so important for early detection, especially in high-risk individuals.

References:

• National Cancer Institute – Merkel Cell Carcinoma Treatment
• The Skin Cancer Foundation – Merkel Cell Carcinoma
• Mayo Clinic – Merkel Cell Carcinoma
• American Academy of Dermatology – Merkel Cell Carcinoma
• American Cancer Society – Merkel Cell Carcinoma