Metachronous Merkel cell carcinoma on both cheeks

Area of Science:

• Oncology
• Virology
• Dermatology

Background:

• Merkel cell carcinoma (MCC) is an aggressive neuroendocrine skin cancer.
• Patients with MCC have an elevated risk of developing secondary primary cancers.
• Merkel cell polyomavirus (MCV) is a recently identified human polyomavirus associated with MCC.

Observation:

• This report details the first documented case of two primary MCCs on a patient's face, occurring sequentially.
• The initial tumor on the right cheek was treated with surgery and chemoradiation.
• A second, distinct MCC developed on the left cheek after a 10-year disease-free interval.

Findings:

• Histological and immunohistochemical analyses confirmed both lesions as MCC.
• Both tumors exhibited high copy numbers of MCV.
• Expression of MCV large T antigen was detected, suggesting its role in oncogenesis.

Implications:

• This case reinforces the strong association between MCC and MCV infection.
• It underscores the potential for multiple primary MCC occurrences in a single patient.
• The findings emphasize MCV's role in the pathogenesis of Merkel cell carcinoma.