Medically inoperable Merkel cell carcinoma of the head and neck treated with stereotactic body radiation therapy: a case report

Merkel cell carcinoma (MCC) is a rare but aggressive neuroendocrine tumour of the skin. MCC is the second most common cause of death from non-melanoma skin cancer and the most aggressive cutaneous malignancy. An 88-year-old male presented with a large, bleeding skin tumour located on the right temple and pre-auricular region. A biopsy confirmed MCC; immunohistochemistry (IHC) was positive for synaptophysin and CK20. The patient was assessed by a head and neck surgical oncologist and not deemed to have operable disease due to medical co-morbidities and extent of disease. The patient underwent a single fraction of electron treatment, followed by stereotactic body radiation therapy (SBRT) to a total dose of 40 Gy in 5 fractions over 2 weeks. Bleeding stopped and the patient tolerated treatment well with no reported side effects other than fatigue. There was symptomatic improvement within 2 weeks and a complete clinical response within 4 weeks of treatment. There are limited data on the use of radiotherapy in unresected/ inoperable MCC. For elderly, medically frail patients who cannot undergo surgery, SBRT may be an option to alleviate symptoms and control the tumour in a relatively short number of treatments; further study is warranted.