Merkel cell carcinoma pictures
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Summary
10 papers analyzed
These studies suggest that Merkel cell carcinoma (MCC) is a rare, aggressive skin cancer with neuroendocrine characteristics, influenced by Merkel cell polyomavirus and UV exposure, and that recent advances in diagnosis and treatment, including immunotherapy, are improving management and prognosis.
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Understanding Merkel Cell Carcinoma: Clinical Presentation and Diagnosis
Introduction to Merkel Cell Carcinoma (MCC)
Merkel cell carcinoma (MCC) is a rare but highly aggressive form of skin cancer with neuroendocrine features. It predominantly affects elderly and immunocompromised individuals and is characterized by its rapid growth and high potential for metastasis . The incidence of MCC is increasing globally, with notable variations across different geographic regions .
Clinical Presentation of MCC
Appearance and Common Sites
MCC typically presents as a solitary, painless, firm, and rapidly growing nodule or plaque on sun-exposed areas of the skin, such as the head, neck, and extremities . These lesions are often red, purple, or skin-colored and can be mistaken for other types of skin cancers or benign conditions .
Histological Features
Histologically, MCC is defined by its neuroendocrine and epithelial differentiation. The tumor cells are small, round, and blue with scant cytoplasm, resembling small-cell carcinoma of the lung . Immunohistochemical staining is crucial for diagnosis, with markers such as cytokeratin 20 (CK20) and neuroendocrine markers like chromogranin and synaptophysin being commonly used .
Pathogenesis and Risk Factors
Merkel Cell Polyomavirus (MCPyV)
A significant proportion of MCC cases are associated with the Merkel cell polyomavirus (MCPyV), which integrates into the host genome and drives carcinogenesis . MCPyV-positive tumors tend to have a better prognosis compared to MCPyV-negative tumors, which are often linked to ultraviolet (UV) light-induced mutations .
UV Light and Immunosuppression
Chronic sun exposure and immunosuppression are major risk factors for MCC. UV light contributes to DNA damage and immunosuppression, facilitating the development of MCC, particularly in MCPyV-negative cases . Immunosuppressed individuals, such as organ transplant recipients and those with HIV, are at a higher risk of developing MCC .
Diagnostic Evaluation
Clinical Examination and Imaging
Early diagnosis of MCC is critical for effective management. Clinical examination should be complemented by imaging studies such as ultrasound, CT, or PET scans to assess the extent of the disease and detect metastases .
Histopathology and Immunohistochemistry
Definitive diagnosis relies on histopathological examination and immunohistochemical staining. CK20 positivity in a perinuclear dot pattern is a hallmark of MCC, along with other neuroendocrine markers . Sentinel lymph node biopsy is often performed to evaluate regional lymph node involvement, which is present in approximately 30% of cases at diagnosis.
Conclusion
Merkel cell carcinoma is a rare but aggressive skin cancer with distinct clinical and histopathological features. Early recognition and accurate diagnosis are essential for effective management. Advances in understanding the role of MCPyV and the impact of UV light on MCC pathogenesis have improved diagnostic and therapeutic approaches, offering hope for better patient outcomes.
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