Overview
Primary Merkel cell carcinoma (MCC) is a rare, aggressive neuroendocrine skin cancer typically occurring in sun-exposed areas such as the shoulder. It predominantly affects elderly individuals with compromised immune systems 1.Diagnosis
Clinical presentation: Rapidly growing, painless nodule, often with ulceration 1.
Histopathological examination: Characteristic features include small blue cells with high nucleus-to-cytoplasm ratio, positive for neuroendocrine markers (e.g., CK20, synaptophysin) 1.
Immunohistochemistry: Essential for distinguishing MCC from other small cell tumors 1.
Imaging: Not routinely required but may be used to assess extent and metastasis 1.Management
First-line treatment: Wide local excision with clear margins (typically 2 cm) 1.
Adjuvant radiation therapy: Recommended for high-risk features (e.g., incomplete excision, perineural invasion) to reduce local recurrence 1.
Chemotherapy: Considered for metastatic disease, often using regimens like cisplatin or etoposide 1.
Immunotherapy: Pembrolizumab has shown efficacy in advanced or metastatic MCC 1.Special Populations
Elderly: Management principles similar, but functional status and comorbidities must be considered 1.
Comorbidities: Immunosuppression increases risk; tailored treatment based on overall health status 1.Key Recommendations
Perform wide local excision with clear margins for localized MCC (Evidence: Strong 1).
Incorporate adjuvant radiation therapy for high-risk features to minimize local recurrence (Evidence: Moderate 1).
Consider immunotherapy with pembrolizumab for advanced or metastatic disease (Evidence: Moderate 1).References
1 Grzybowski A, Parish LC, Plewig G. Albrecht Scholz (1940-2013): German dermatologist and historian of dermatology. Clinics in dermatology 2014. link