A 21-year course of Merkel cell carcinoma with adjuvant Viscum album extract treatment: A case report.

BACKGROUND: Merkel cell carcinoma (MCC) is a rare, aggressive, neuroendocrine skin tumor with frequent local recurrence, lymph node involvement, distant metastasis, and a high mortality rate. Viscum album extracts (VAE) are a widely used adjunct in cancer treatment and show cytotoxic and immune-modulating effects.

CASE PRESENTATION: A 64-year-old woman was diagnosed with a MCC of the left forearm. In the following course of 21 years, she experienced 4 episodes of lymph node relapse (axillary, submandibular, axillary, clavicular). All lesions were surgically excised. The patient declined chemotherapy and radiation and opted for adjuvant treatment with local subcutaneous VAE injections. Currently-21 years after first diagnosis and 9.5 years after the last relapse-the patient is tumor-free, in good health, and without functional limitations.

CONCLUSION: The presented case shows long-time survival in a patient with MCC treated with surgery and VAE injections. The immune system plays a key role in tumorigenesis of MCC. VAE enhances several immune pathways and might therefore contribute to immunologic tumor control in MCC. The role of VAE in MCC should further be investigated.