Spontaneous remission of Merkel cell carcinoma presenting with tertiary lymphoid structures in an immunocompetent patient.

Dear Editor, Merkel cell carcinoma (MCC) is a rare and aggressive neuroendocrine skin cancer predominantly affecting elderly males, with a median age at diagnosis of 76 years. Its pathogenesis is linked to three main risk factors: UV exposure, Merkel cell polyomavirus (MCPyV) infection, and immunosuppression. Standard management of localized disease (stage I/II) consists of wide local excision with sentinel lymph node biopsy (SLNB), followed by adjuvant radiotherapy according to disease stage. Despite optimal multimodal treatment, prognosis remains poor, with more than 50% of patients progressing to metastatic disease and a median overall survival of approximately 20 months with first-line avelumab. [...].