Merkel Cell Carcinoma: A Meticulous Literature Appraisal

Abstract

Merkel cell carcinoma represents an uncommon yet highly aggressive cutaneous malignancy of neuroendocrine origin, with a steadily rising incidence reported worldwide. This review aims to evaluate and summarize current evidence on the diagnosis, staging, and management of Merkel cell carcinoma. A comprehensive literature search was performed across PubMed, Embase, and Google Scholar to identify studies published between 2005 to 2024 addressing the diagnosis, staging, and management of Merkel cell carcinoma. Search terms included “Merkel cell carcinoma” combined with “diagnosis,” “staging,” “surgery,” “radiotherapy,” and “systemic therapy.” Merkel cell carcinoma frequently presents as a rapidly enlarging, firm, violaceous nodule on sun-exposed skin. Diagnosis relies on histopathology and immunohistochemistry, with characteristic CK20 and neuroendocrine marker positivity. PET/CT outperforms conventional imaging for detecting nodal and distant metastases. Sentinel lymph node biopsy is critical for staging clinically node-negative cases. Treatment is stage-driven and multidisciplinary. Wide local excision with ≥1–2 cm margins remains the surgical standard. Adjuvant radiation enhances loco-regional control, particularly in cases with positive margins, LVI, or immunosuppression. While chemotherapy offers a limited benefit. Immunotherapy has redefined first-line therapy in advanced disease. Emerging targeted therapies hold promise for patients with refractory disease. Future directions in Merkel cell carcinoma management are predicted to emphasize the identification of predictive biomarkers for treatment response, the advancement of novel immune and molecularly targeted therapies, and the optimization of radiotherapy through hypo-fractionated and image-guided approaches. A multidisciplinary, timely, and personalized treatment approach is crucial for optimizing outcomes.