Merkel Cell Carcinoma (MCC) is a rare, highly aggressive neuroendocrine skin cancer originating in epidermal Merkel touch cells.
Causes & Risk Factors
• Merkel Cell Polyomavirus (MCPyV): Integrated into tumor cell DNA in 80% of cases.
• UV Radiation: Chronic exposure on sun-exposed face, neck, arms.
• Risk factors: Age >50 (median 74), immunosuppression (HIV, transplant, leukemia), fair skin, male.
AEIOU Mnemonic & Symptoms
Pink/red/purple painless nodule expanding rapidly over weeks.
AEIOU Mnemonic: Asymptomatic, Expanding rapidly, Immune suppressed, Older than 50, UV-exposed fair skin site.
Diagnostics, SLNB & Immunotherapy
Diagnostics: Skin biopsy showing small round blue cells, IHC positive for Cytokeratin-20 (CK20 perinuclear dot pattern 90%), Synaptophysin, SLNB, CT/MRI/PET-CT.
Treatment: Wide Local Excision WLE (1-2 cm margins), SLNB, Adjuvant Radiation, Lymph node dissection, Immunotherapy (Avelumab, Pembrolizumab), Chemotherapy (Cisplatin/Carboplatin + Etoposide).
Prognosis: 5-yr survival Stage I 75%, Stage II 60%, Stage III 40%, Stage IV 20-24%.