MERKEL CELL CARCINOMA (MCC)

Merkel Cell Carcinoma (MCC) is a rare, highly aggressive, and potentially life-threatening form of skin cancer that originates in Merkel cells — specialized neuroendocrine cells located at the base of the epidermis (outermost skin layer). These cells are involved in the sensation of touch and are closely associated with nerve endings.

Unlike other skin cancers like basal cell carcinoma or squamous cell carcinoma, MCC is characterized by rapid growth, early local invasion, and a high risk of metastasis to lymph nodes, distant skin sites, and organs like the lungs, liver, bones, and brain.

Though rare (about 3,000–3,500 new cases annually in the U.S.), the incidence of MCC has risen by 95% over the past 20 years, partly due to improved detection and increased lifespan of immunocompromised patients.

CAUSES AND RISK FACTORS

The exact cause of Merkel Cell Carcinoma remains unclear. However, several risk factors have been strongly associated:

Key Causes:

• Merkel Cell Polyomavirus (MCPyV):
  • Discovered in 2008, this common virus is integrated into the DNA of tumor cells in about 80% of MCC cases. Although many people carry MCPyV, it rarely causes cancer unless the immune system is weakened.
• Ultraviolet (UV) Radiation:
  • Chronic exposure to UV light from sun or tanning beds increases the risk. MCC frequently occurs on sun-exposed areas, such as the face, neck, and arms.

Risk Factors:

• Age:
  • Primarily affects individuals over 50 years (median age at diagnosis: 74).
• Immunosuppression:
  • People with HIV/AIDS, organ transplant recipients, leukemia, or lymphoma patients, and those on long-term immunosuppressive medications are at higher risk.
• Fair Skin:
  • Light-skinned individuals are more susceptible due to lower melanin levels.
• Male Gender:
  • MCC is slightly more common in men.
• Prior Skin Cancers:
  • History of melanoma or non-melanoma skin cancers increases the risk.

SYMPTOMS

Merkel Cell Carcinoma typically presents as a painless, firm, and rapidly growing nodule. Symptoms can include:

Primary Skin Symptoms:

• Pink, red, purple, or bluish nodule
• Dome-shaped, raised, or flat lesion
• Rapid enlargement over weeks or months
• May ulcerate or bleed
• Common locations: head, neck, arms, legs, and torso

Systemic Symptoms (if advanced):

• Enlarged lymph nodes
• Fatigue
• Weight loss
• Bone pain (if metastasized to bones)
• Shortness of breath (if lung metastases)
• Neurological symptoms (if brain metastases)

Mnemonic for MCC lesions:

AEIOU:

• Asymptomatic (painless)
• Expanding rapidly
• Immune suppression
• Older than 50
• UV-exposed site on fair skin

DIAGNOSIS

Early diagnosis is crucial for MCC due to its aggressive nature.

Diagnostic Methods:

• Physical Examination:
  • Assess suspicious lesions and lymph node involvement.
• Skin Biopsy:
  • A full-thickness excisional biopsy is performed. Histopathology typically shows small, round, blue tumor cells with scant cytoplasm.
• Immunohistochemistry (IHC):
  • Confirm diagnosis using specific tumor markers:
    • Cytokeratin-20 (CK20): Perinuclear dot-like pattern (positive in 90% cases)
    • Synaptophysin, Chromogranin A: Neuroendocrine markers
    • Imaging Tests:
      • CT Scan, MRI, or PET-CT for staging and to detect distant metastases.
      • Sentinel Lymph Node Biopsy (SLNB):
        • Identifies microscopic metastasis in regional lymph nodes.

STAGING

Merkel Cell Carcinoma is staged based on the AJCC (American Joint Committee on Cancer) 8th edition:

PREVENTION & EARLY DETECTION

Though not entirely preventable, risk can be reduced by:

• Limiting sun exposure and avoiding tanning beds
• Regular use of SPF 30+ sunscreen
• Wearing protective clothing
• Performing regular skin self-exams
• Annual dermatological evaluations, especially for high-risk individuals
• Managing underlying immunosuppressive conditions

TREATMENT FOR MERKEL CELL CARCINOMA

Treatment depends on tumor stage, location, and patient’s general health.

Localized Disease (Stage I-II):

• **Wide Local Excision (WLE):**urgical removal with 1-2 cm margins.
• Sentinel Lymph Node Biopsy (SLNB):
  • Performed concurrently to detect microscopic spread.
• Adjuvant Radiation Therapy:
  • Reduces local recurrence risk.

Regional Disease (Stage III):

• Lymph Node Dissection:
  • Removal of affected lymph nodes.
• Radiation Therapy:
  • To primary site and regional nodes.
• Immunotherapy (preferred systemic treatment):
  • Avelumab (anti-PD-L1)
  • Pembrolizumab (anti-PD-1)

High response rates and improved survival.

Advanced or Metastatic Disease (Stage IV):

• Immunotherapy (first-line):
  • Avelumab or Pembrolizumab.
• Chemotherapy (if immunotherapy unavailable):
  • Cisplatin + Etoposide
  • Carboplatin + Etoposide

(Limited efficacy, short-lived response)

• Palliative Radiation:
  • For symptom control.

PROGNOSIS

Merkel Cell Carcinoma is aggressive, with prognosis dependent on stage and timely treatment.

Key prognostic factors:

• Tumor size
• Lymph node involvement
• Immune status
• Timeliness of treatment

FOOD & DIET FOR MCC PATIENTS

While no diet can cure MCC, proper nutrition supports immunity, helps treatment side effects, and aids recovery.

Recommended Foods:

• Lean proteins: chicken, turkey, fish, legumes
• Omega-3-rich foods: salmon, walnuts, flaxseeds
• Whole grains: brown rice, quinoa
• Antioxidant-rich fruits: berries, citrus
• Leafy greens: spinach, kale
• Hydrating foods: cucumber, watermelon
• Herbal teas: green tea

Foods to Avoid:

• Processed meats and snacks
• Sugary beverages and refined sugars
• Excessive sodium and salt-laden foods
• Excess alcohol
• Deep-fried and greasy foods

Immune-Boosting Nutrients:

• Vitamin C: Citrus, bell peppers
• Vitamin E: Almonds, sunflower seeds
• Zinc: Pumpkin seeds, chickpeas
• Selenium: Brazil nuts
• Probiotics: Yogurt, kefir

FAQs

1. Is Merkel Cell Carcinoma curable?

   Yes — early-stage MCC can be cured with surgery and radiation. Advanced cases respond well to immunotherapy.

2. How quickly does MCC grow?

   Very rapidly — it often doubles in size within weeks.

3. Can MCC return after treatment?

   Yes — it has a high recurrence rate within 3 years.

4. Is MCC painful?

   Most lesions are painless at first.

5. Can MCC spread to the brain?

   Rare, but possible in advanced stages.

6. Can MCC affect young people?

   Uncommon, but has been reported in immunocompromised young adults.

7. How is MCC different from melanoma?

   MCC is rarer, more aggressive, often painless, and associated with a virus.

8. Are there clinical trials for MCC?

   Yes — ongoing studies in immunotherapy and virus-targeted therapies.

9. Should immunocompromised people be screened for MCC?

   Yes — regular skin exams are recommended.